Mather Field Vernal Pools Algae - Sacramento Splash · Heliozoa is a protozoan that looks like a soccer ball with spikes. The spikes are covered with a sticky substance that is poisonous

Mather Field Vernal Pools

© Bruce Russell, BioMEDIA ASSOCIATES

© Ken Davis

common name Algae

scientific name

There are thousands of species of freshwater algae. Three vernal pool algae are: Volvox, Chara and Zygnema.

classifi- cation

Most algae are plants. Some are in a special group that is neither plant nor animal.

habitat most aquatic habitats on Earth

size mostly microscopic

description Algae live in water and come in many shapes and sizes. They are shades of green, golden brown, red, or brown. Like other plants, algae are made up of cells like building blocks. You can see the cells only under a microscope. Algae cells contain green chlorophyll. Chlorophyll captures the sun's energy and turns it into food through a process called photosynthesis.

Some species of algae are just a single cell that lives alone. Other species live together in groups. The cells of some algae, such as the Zygnema in vernal pools, are linked together to make long threads. Big clumps of Zygmena look like green clouds floating in the water. Some vernal pools are totally green with Zygnema.

fun facts A beautiful algae called Volvox is really a colony of algae cells living together in a sphere. It looks like a green globe spinning slowly through the water. It is macroscopic, so you can see it with a hand lens. Sometimes you can find a microscopic critter called a Rotifer living inside of a Volvox. This species of Rotifer is a parasite. It munches away on the cells of the Volvox and lays eggs. The damage slowly destroys the perfect globe shape of the Volvox. When the Rotifer has eaten enough, it escapes and swims off to find and parasitize another Volvox.

life cycle Most Algae divide to reproduce. They simply split in half to become two Algae.

Other species have male and female reproductive parts. Algae in vernal pools can produce spores that can survive harsh, dry conditions for many years.

ecology Algae are important in the vernal pool food web. With their green chlorophyll

and carbon dioxide from the air, Algae capture the energy of sunlight to make their own food. The food that Algae produce is a form of energy that other species can use. Algae are eaten by Protozoa, Rotifers, Water Fleas, Seed Shrimp, Flatworms, Copepods and many small aquatic animals. Not only do Algae pump energy into the vernal pool ecosystem, they also pump oxygen into it. When Algae make food, they also make oxygen. This oxygen dissolves into the water, where other vernal pool critters can use it.

Clouds of Algae give Tadpole Shrimp and aquatic insects a place to hide from birds. When the pools begin to dry up, the clouds of Algae can no longer float. Then, Algae forms a thin mat on top of the young vernal pool plants. When this algal mat dries, it makes an umbrella or canopy above the ground.

investigate Zygnema can form algal mats in some pools. Young frogs, toads and other

species can be found under the algal mats even in July, long after the pools have dried. Take a peek under the canopy and see what species depend on the mat for shade, dampness and shelter.

Scientists use special meters (electronic measuring tools) to measure the amount of oxygen dissolved in water. If you had a dissolved oxygen meter, would you expect to find more oxygen in a vernal pool during the day or at night? Why? Hint: When do algae and other plants make food (and oxygen)?

What is an algae bloom?

Some algal species are very sensitive to the pollution in runoff, especially fertilizers from lawns and gardens. The number of algae in polluted water can grow quickly into an "algae bloom." This knocks the food web out of balance, damaging other aquatic species.

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© Ken Davis

common name Bacteria

scientific name over 100,000 different species

classifi- cation Kingdom: Bacteria

habitat Every habitat on Earth contains bacteria, including vernal pools, lakes and streams.

size Bacteria are microscopic. They are invisible to the naked eye. Microscopes make them appear 100 to 400 times bigger, but even then you can barely see some of them.

description Bacteria are black or clear unless you stain them with special dyes to see them

better. Bacteria are made up of one cell. It can be round, long and thin, or spiral shaped.

fun facts There are thousands of different species of bacteria. Most species live only in

certain habitats. Others are found in many different places. Bacteria are the toughest life forms on Earth. In some harsh environments, like boiling hot springs, they are the only form of life.

For 2 billion years, bacteria were the only creatures on Earth. Long before the dinosaurs, a special type of bacteria slowly increased the level of oxygen in the Earth's air to 20 percent. Without this oxygen other plants and animals could not have evolved, including us.

People use bacteria to make certain foods and drugs. Bacteria turn milk into cheese and yogurt. Bacteria help us digest our food. In fact cows and sheep cannot digest grass without certain species of bacteria in their intestines. Some bacteria can cause diseases in humans and other species.

life cycle The life cycle of bacteria is very fast. Bacteria reproduce by dividing their one

cell into two identical cells. Some bacteria can divide every fifteen minutes. The size of their populations can increase very quickly, providing lots of food for other species.

ecology Bacteria are necessary for a vernal pool ecosystem to function. When rainwater

dampens vernal pool soils, the bacteria start to eat detritus (dead plants) lying on the ground. By decomposing the detritus, bacteria release its nutrients. The nutrients act like a natural fertilizer that helps algae to grow. The algae and growing numbers of bacteria in the water become a "living soup." This soup feeds the protozoa, seed shrimp, waterfleas, fairy shrimp and many other animals that will soon hatch.

The most important role of bacteria in most food webs is to decompose (break down) the bodies of dead plants and animals. Life on Earth would be much different if bacteria did not perform this function. Dead plants and animals would not rot. Our world would be littered with dead stuff. There would be no nutrients or food for other living things to eat. The whole food web would stop cycling energy through it.

other Cyanobacteria (picture above) are the oldest known fossils, more than 3.5

billion years old. They still live in aquatic habitats around Sacramento especially in polluted water. They can be used as a sign to indicate water pollution. We rarely see cyanobacteria in vernal pools because the pools are a clean aquatic habitat.

investigate As you learn about the other creatures that live in vernal pools, make a list of

the species that are connected to bacteria through the vernal pool food web.

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© Ken Davis

common name

Muck, Rotting Stuff, Detritus

scientific name

Detritus (pronounced di-TRY-tis)

habitat bottom of vernal pools and other water bodies

size microscopic to big chunks

description Detritus is all the dead stuff that sinks to the bottom of a vernal pool. It contains

pieces of dead plants, dead animals and animal wastes (feces). It is usually black or brown. Although detritus is dead, it is crawling with living microscopic critters.

fun facts The larva of a midge (a type of fly) lives in the detritus on the bottom of some

vernal pools. The midge larva looks like a worm with a hard, brown head. It makes a sack for itself (like a sleeping bag), which it covers with detritus. The detritus cover is perfect camouflage to hide the midge larva from its predators. It is almost invisible as it hunts for food on the bottom of a vernal pool.

ecology Detritus is very important to the vernal pool food web. Almost any critter that

lives in a vernal pool either eats detritus or a critter that eats detritus. Detritus is covered with many species of Bacteria. Bacteria are decomposers. When Bacteria eat detritus, they are recycling the energy from the dead bodies of plants and animals into their own living bodies. The mix of detritus and Bacteria is then eaten by Protozoa, aquatic earthworms, Seed Shrimp, Water Fleas, Rotifers, Copepods, Fairy Shrimp and Tadpole Shrimp.

Detritus provides a home for many small critters that live on the bottom of a vernal pool. Detritus is always being made, because something is always dying (or dropping feces) in this busy food web. The recycling of detritus shows us that death is an important part of life in every vernal pool.

investigate With help from your classmates, make a list of all the vernal pool species that

eat detritus. Imagine what would happen if there were no decomposers in the vernal pool food web.

When you visit vernal pools, be sure to look for a midge larva camouflaged with detritus. Watch how it slides its head out of its protective sack to hunt for food.

Few people have heard of the large group of flies called midges. Search for more information about midges. Does the adult midge look like any other flyinginsect that you know?

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© Ken Davis

common name Protozoa

scientific name

There are thousands of species of protozoa. Some groups found in vernal pools are: Vorticella, Heliozoa, and Ameoba

phylum Protozoa

habitat most aquatic habitats on earth

size microscopic, 2 to 70 microns (0.002 to 0.07 mm)

description Protozoa are single-celled animals that come in many shapes and sizes. The

most common shapes are round, oval, bell-shaped and slipper-shaped. Protozoa are clear. They become the color of the materials inside them, including the food they just ate.

fun facts Some species of protozoa use other vernal pool critters as taxis! With a

microscope, you can see a species of Vorticella attached to the bodies of Seed Shrimp and Water Fleas. The Vorticella gets a free ride, and finds food along the way.

A different vernal pool species of Vorticella lives in groups. They let a certain species of green algae live inside their bodies. Some scientists believe that the Vorticella are "farming" the algae. This means that they use the food produced by the algae for themselves.

Heliozoa is a protozoan that looks like a soccer ball with spikes. The spikes are covered with a sticky substance that is poisonous to other protozoa. Any protozoan that touches Heliozoa is instantly paralyzed. Heliozoa sucks out the insides of its prey and eats it.

life cycle Most protozoa reproduce by cell division. The cell splits apart and forms two

cells that are identical to the original cell. When food runs out or it becomes too dry and hot in a vernal pool, protozoa form a resting cyst with extra layers of walls around it. The walls protect the cyst until the pools are wet again. They hatch in just a few minutes once the rains return in winter.

ecology Protozoa eat bacteria, detritus, algae and other protozoa. Protozoa are eaten by Water Fleas, Flatworms, Seed Shrimp, Clam Shrimp and many other vernal pool invertebrates.

investigate Find out which vernal pool species eat critters that feed on protozoa?

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© Ken Davis


common name Rotifers

scientific name many different species

phylum Rotifera

habitat vernal pools and other aquatic habitats

size microscopic, 100 to 500 microns (0.1 to 0.5 mm)

description Rotifers are the smallest animals. Their outer coat looks like clear glass. Sometimes this glassy coat is covered with spines or spikes. Rotifers have a ring of cilia (hairs) at their head end. The cilia beat in a wave, making currents to bring in food particles. Rotifers have real organs, including a brain, stomach and intestines. Rotifers are usually transparent, so you can see their organs. You can also see the color of the food they just ate!

fun facts A vernal pool is a great place to see Rotifers. You can easily find 20 different

species. Some are attached to plant stems. Others swim through the water. One Rotifer is a parasite! It lives inside of a beautiful algae called Volvox. The Volvox is a colony of algae cells that live together in a sphere. It looks like a green globe spinning slowly through the water. It is macroscopic, so you can see it with a hand lens. (You can see a picture of Volvox on the Critter Card for Algae.)

The parasitic Rotifer lives inside the Volvox. It munches away on the colony and lays its eggs. The damage slowly destroys the perfect globe shape of Volvox. When the Rotifer has eaten enough of its host, it escapes and swims off to find another victim.

life cycle A vernal pool Rotifer can survive the hot, dry Sacramento summer. When its vernal pool dries up, so does the Rotifer! The Rotifer becomes very wrinkled and dry. It is smaller than a piece of dust. When the pool fills with water, the dried up Rotifer returns to its normal shape and its normal life. Scientists have seen Rotifers come back to life that were kept dry for 27 years!

Most of the Rotifers in vernal pools are females. Each female can reproduce all by herself, without the help of a male. She makes fertile eggs. The young Rotifers are exact copies of their mother. This kind of reproduction is called parthenogenesis.

ecology Many different species of Rotifers live in vernal pools. Some species live alone.

Others live in colonies. Some attach themselves to plants. Others swim freely through the water. As you know, at least one is a parasite.

A Rotifer beats its cilia to suck detritus, Algae, Bacteria and Protozoa into its stomach. Many critters eat Rotifers including: Clam Shrimp, Fairy Shrimp, Tadpole Shrimp, Water Fleas, tadpoles, aquatic insects, Mallards and other ducks, and Great Egrets and other wading birds.

investigate When you visit vernal pools, look for the bright green Volvox colonies floating

in the water. Ask your guide to put one under a microscope, so you can look for the parasitic Rotifer inside. If the parasites are around, some of the Volvox colonies will look a bit ragged or torn. See if you can find other Rotifers under the microscope.

Now you know that Rotifers live in vernal pools. So, where else do Rotifers live? If you can use a microscope, you can solve the mystery. Even the lowest power of a compound microscope will help you to spot Rotifers. Ask your teacher if a microscope can be brought into your classroom.

You can collect a water sample from any kind of water or wet place such as a wetland, bird bath, dog's water bowl, roadside puddle, clump of moss or wet sand. Do not worry if the "wet" habitat has dried up. Just take a sample of the dry material from the bottom and add bottled water. Any dried Rotifers will come back to life within an hour.

Put your water sample on a glass slide or in a Petri dish. You can even put somewater in a clean, zipper-lock sandwich bag. (When you lay the bag on its side, the water should be less than 1 cm deep, with no air bubbles. With some help from your teacher, slide the sample under the microscope lens and search for Rotifers. You can find out more about Rotifers on the web and in books.

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© Ken Davis

common name Aquatic Snails


phylum class

Mollusca Gastropoda

habitat most shallow freshwater habitats, including ponds, lakes, creeks, rivers, and vernal pools

size less than 12.5 mm long

description Freshwater snails are not as colorful as their saltwater cousins. In general, their

shells come in shades of gray, brown, and black, often with flecks of yellow or white.

Vernal pools have their own species of aquatic snails. Two aquatic snails are often seen in ponds and creeks of the Sacramento area. One is shaped like a flat spiral, and the other looks like a turban. Sticking out under the shell is the "foot". The foot is fleshy and muscular; it allows the snail to move around. The foot extends to a head, with two tentacles on it like antennae. The eyes are located on or near these tentacles.

fun facts In preparation for the dry summer, the snails burrow several inches into the

mud and seal themselves in mucus to prevent water loss. They can stay like this for up to three years!

life cycle Eggs are laid in jelly-like capsules on rocks or plants at the water’s edge. When

the eggs hatch tiny snails emerge. They gradually grow to adult size. ecology Using a long, rough tongue, the aquatic snail scrapes organic material, like

algae and detritus, into its mouth. The snails serve as food for many different animals. Common predators include ducks, shore birds, amphibians, and aquatic insect larvae. In lakes and streams, fish often eat them.

investigate Little is known about the aquatic snail species that live in vernal pools. Do you

think snails could travel across the grasslands from one pool to another without

drying out? What ways can you think of that aquatic snails could get from one pool to another? Could other animals in the vernal pool grassland ecosystem carry them as they travel from pool to pool?

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© Ken Davis

common name Flatworms

scientific name many species

phylum class

Platyhelminthes Turbellaria

habitat vernal pools, vernal swales and freshwater marshes

size 0.5 mm to 1 cm long

description Although they are called Flatworms, these invertebrates are not flat. They are round-bodied with a flat belly. They are longer than they are wide. They are pointed at each end. Most Flatworms have at least two eyespots close to the head end of the body.

At least 20 species of Flatworms live in vernal pools. Three species are easy to find in the Sacramento's vernal pools. The first Flatworm, Mesostoma,is translucent and white. The second Flatworm is translucent and green. It has green algae living in its body. The third Flatworm is dark brown and blotchy or mottled on its upper side.

fun facts A Flatworm has a single opening to its stomach, in the middle of its underside.

The Flatworms in vernal pools can stick this pharynx (throat/mouth) into their

prey. Like a short vacuum cleaner hose, it sucks out the insides of their prey. They also use it to push wastes out of their bodies.

life cycle Flatworms are one of the first critters to hatch when the pools start filling with

rainwater. The young hatch from eggs and look similar to the adults. When they are mature, Flatworms mate and lay dark, round eggs. Most Flatworms are hermaphroditic, meaning they are both male and female. Every Flatworm can mate with any other Flatworm if it is the same species.

ecology Flatworms are eaten by the adults and larvae of Aquatic Beetles. The

Flatworms in vernal pools eat Bacteria, Algae, Protozoa, and small invertebrates such as Fairy Shrimp. Some Flatworms scavenge on dead and dying invertebrates.

The white Flatworm, Mesostoma, hangs a thread of slime in the water to trap Water Fleas. It returns to check its "trap line" to harvest any Water Fleas caught in the slime.

A Flatworm moves by rowing its many tiny, thin, hair-like structures called cilia on the outside of its body. Its flat belly allows it to glide on the water surface, while its cilia gently move it along in search of food or a mate.

investigate Watch for the brown Flatworms that glide on the surface of the vernal pools.

They respond to vibrations on the water surface to hone in on prey. If an insect drops (or you tap) on the water surface, the Flatworms will move toward the disturbance, hoping to catch some prey in distress.

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© David Rosen

common name Water Mite

scientific name Hydrachna species

phylum subphylum class order family

Arthropoda Chelicerata Arachnida Acarina Hydrachenellae

habitat vernal pools, other ponds and slow moving streams

size 2 to 3 mm long

description Several species of Water Mites live in vernal pools. The most obvious one looks like a fat spider with a bright red, round body. It has eight small legs attached near the front end of its body. You can find the adult swimming on the surface of the pools, or scrambling around eating plants underwater.

fun facts The larva of this red species of Water Mite is a parasite on the Water Boatman.

The Water Boatman is a common insect in vernal pools. The Water Boatman helps the Water Mite larva in two ways. It shares its energy and provides a free taxi service. The Water Mite larva attaches to a Water Boatman and sucks out some of its body fluids for energy. When a Water Boatman flies to other vernal pools, it carries the Water Mite larva along. One Sacramento scientist collected 100 Water Boatmen from a vernal pool. He marked each one with a tiny drop of nail polish. Two weeks later, he found two of the marked bugs in a vernal pool 70 miles away! Any Water Mite larvae on those two Water Boatmen got a long ride to a new vernal pool.

life cycle Water Mites go through four stages of life: egg, larva, nymph and adult. When a vernal pool fills with water, the larvae hatch out of the eggs. Each larva needs to find a Water Boatman to parasitize. The larva will cling to the outside of a Water Boatman until the larva is fully grown. Then it drops off the host and turns into a nymph. The nymph is a predator that swims in the vernal pool. When the nymph is ready to become an adult, it clings to an underwater plant and changes into its adult form. After finding a mate, the female produces a jelly-like glob of eggs, which she attaches to a plant. Then she dies. The eggs remain there as the pool dries up. They are adapted to survive the long, hot summer. When the winter rains fill the vernal pool, the Water Mite repeats its life cycle.

ecology When a Water Mite larva hatches, it attaches to a weak spot in a Water

Boatman's exoskeleton (outside shell), usually near the head. The larva sucks body fluids out of the Water Boatman. The larva eventually drops off its host and molts to become a nymph. The nymph is a predator that grabs young Water Fleas and Seed Shrimp. It sucks nutritious juice out of them with its piercing mouthparts. It also snacks on Aquatic Snails. Then the nymph turns into an adult. The adult is an herbivore. It feeds on plants in the vernal pool to gather the energy to search for a mate and produce eggs. Biologists have not reported which species prey on the Water Mite eggs, larva, nymphs or adults. However, it is likely that they are eaten when Mallards and other ducks filter vernal pool water with their bills.

investigate The bright red color of an adult Water Mite probably comes from the food it

eats. This bright color seems like it would attract predators, much like a red sign that says, "Eat me". However, sometimes bright colors act as a warning sign to predators to say, "Remember me? I tasted bad" or "I made you sick once". Identify another critter in vernal pools that is bright red. Talk to the student studying this species to see what eats it. Think about ways you could discover what eats Water Mites in vernal pools.

Sometimes species have bright colors to help attract a mate. Some of the male birds in the vernal pool grasslands have bright colors to attract females. Talk to your classmates to discover which bird species use color this way. Is it possible that the bright red of a Water Mite adult helps it to attract a mate? Can you think of ways you could investigate this hypothesis?

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© David Rosen


common name Clam Shrimp

scientific name

Cyzicus californicus (California Clam Shrimp) Lynceus brachyurus (Lentil Clam Shrimp)

phylum subphylum class order

Arthropoda Crustacea Branchiopoda Conchostraca

habitat seasonal wetlands including vernal pools, vernal swales and watering ponds (for cattle)

size Cyzicus up to 2 cm long Lynceus up to 0.4 cm long

description A Clam Shrimp looks like a small clam. Two shells cover its body. Between the shells you can see two body sections below the head. The front section is the thorax and the back section is the abdomen. The Clam Shrimp has 14 pair of appendages that look like legs. The appendages help the Clam Shrimp to swim, but they are mostly used for collecting food and oxygen.

description (continued)

The California Clam Shrimp is yellow to brown. It is flat and about the size of a dime when it is fully grown. The Lentil Clam Shrimp is smaller and more round. It is shaped like a lentil (a small, flat pea).

fun facts The Clam Shrimp's appendages are covered with feathery gills. The Clam

Shrimp moves them through the water to make a current. This current is strong enough to pull tiny particles of food toward the Clam Shrimp. In this way, a Clam Shrimp can stay in one place and feed.

life cycle Clam Shrimp mate before their vernal pool dries up. The female lays her cysts, which survive the long, hot summer in dried mud. These cysts hatch when the pool fills with rainwater. The larva of a Clam Shrimp looks nothing like an adult. It will go through several larval stages before it gets a shell.

A Clam Shrimp soon outgrows its first shell. It sheds the old shell and replaces it with a new soft shell. The soft shell stretches and hardens to fit the Clam Shrimp's bigger body. This process is called molting. As the Clam Shrimp continues to grow, it will molt several more times. The adults can live for several months, or until the water is gone.

ecology California Clam Shrimp are one of the largest crustaceans in Sacramento's

vernal pools. They live only in big or deep vernal pools because they take a long time to mature and reproduce. In Sacramento, the pools that dry up before May rarely have California Clam Shrimp.

Clam Shrimp are omnivores, meaning they eat both plants and animals. They eat Algae, detritus, Bacteria, Protozoa and Rotifers. The California Clam Shrimp feeds in three ways. It can nibble on the Algae growing on plants or on the bottom of the vernal pool. It can bury itself in the muddy bottom and draw in food by waving its feathery appendages. It can also swim and filter food as it moves through the water. Clam Shrimp are strong swimmers but they usually only swim short distances.

Clam Shrimp are eaten by amphibians, such as the Western Spadefoot, Pacific Chorus Frog and California Tiger Salamander. Other predators include Mallards and other ducks, shore birds like the Killdeer, Great Blue Herons, Great Egrets and other wading birds. The protein from Clam Shrimp provides important nutrition for migrating birds. They visit the vernal pools to quickly gather the nutrients they need to grow new feathers, migrate and lay their eggs.

investigate Clam Shrimp filter feed in the same way as Fairy Shrimp and Tadpole Shrimp.

Do they eat the same kinds of food? Are they eaten by the same predators? Talk with the Fairy Shrimp and Tadpole Shrimp experts in your class to find out.

California Clam Shrimp are one of the few crustaceans that you can find after the vernal pools dry up. Their large shells remain on the pool bottom after they die. If you walk and look carefully, you can find them lying there.

If you had to look in every vernal pool for Clam Shrimp shells, it would take a lot of time. It would be better to look only in vernal pools that are likely to have Clam Shrimp. What do you know about the ecology of Clam Shrimp that tells you what kind of pools to look in?

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© Ken Davis

common name Copepods

scientific name

many different vernal pool species, most without names

phylum subphylum class

Arthropoda Crustacea Copepoda

habitat vernal pools, lakes, ponds, oceans

size up to 3 mm long

description There are many different species of Copepods. Few of the species in vernal pools have been named. You are most likely to spot the bright red Diaptomus and at least one green copepod species in Sacramento's vernal pools. Copepods have four or six legs, a short tail, and long antennae.

fun facts The cysts of Copepods can survive on the bottom of a vernal pool for a long

time. When scientists found Copepod cysts that were 300 years old, they put them in water and watched them hatch!

life cycle Copepods can reproduce in two ways: male and female Copepods can mate or

female Copepods can produce cysts without the help of a male. The female carries the cysts in sacs near the base of her abdomen. When she lays her cysts, they fall to the bottom of the vernal pool. Some of the cysts will hatch right away and the young Copepods will grow quickly. The first stage of a Copepod'slife is spent as a larva. The larva looks very different from the adult Copepod. When the larva is fully grown, it will metamorphose into the adult form.

There may be time for several generations to reproduce before the vernal pool dries up. The other cysts can wait in the bottom of the pool for many years before hatching. When the pool dries up, the cysts remain buried in the hot, dry bottom waiting for the return of winter rains.

ecology Some copepods eat detritus, Bacteria, and Algae. Others, like the red

Diaptomas, are predators that eat tiny Water Fleas, Seed Shrimp and other species of Copepods. In vernal pools, copepods are eaten by Vernal Pool Tadpole Shrimp, Flatworms, Aquatic Beetle larvae and other aquatic insect larvae, wading birds, Mallards and other ducks that filter them out of the water with their bills.

investigate When you visit a vernal pool, watch how the Copepods move through the

water. What part of their bodies do they use to swim? How do their jerky movements help them to avoid predators?

Copepods are important in many food chains

Many Copepods live in freshwater habitats such as lakes, ponds, and vernal pools. But most of the 7500 species of Copepods in the world live in saltwater, which covers 75% of the Earth's surface. Wherever they live, Copepods are an important link in the food web. Many larger animals, like whales and fish, eat saltwater Copepods. Some whales, like the humpback whale, feed almost entirely on Copepods.

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© Ken Davis

common name Fairy Shrimp

scientific names

Linderiella occidentalis Branchinecta lindahli and other species


Arthropoda Crustacea Branchiopoda Anostraca

habitat vernal pools

size 10-44 mm long description Fairy Shrimp are pale-colored (normally gray-white) and transparent. They

have a long, narrow body with 11 pairs of paddle-like legs. Females have a brood pouch which holds eggs located directly behind the legs.

fun facts The Fairy Shrimp that inhabit vernal pools are very small, but some species of

Fairy Shrimp are huge. One species, Branchinecta gigas, lives in muddy, plant-less, desert lakes, and can grow to 150 mm. That's about the size of a hot dog!

life cycle Fairy Shrimp cysts hatch as soon as there is water in the vernal pools.

Individuals grow quickly and can reach maturity in 18-60 days depending upon species and the pool conditions. After the adults mate, cysts begin to develop in the female's brood pouch. Once the cysts are fully formed, they are released and sink to the vernal pool bottom. The female may mate again and repeat the process. A single female can produce several hundred cysts during one season. The cysts usually remain dormant until the next year's rain, but they can last for decades.

ecology Fairy Shrimp suck water through filters and eat the particles that they strain out

of the water. These include bacteria, algae, protozoa, rotifers, and detritus. Fairy Shrimp are a main food source for many creatures. They are eaten by Tadpole Shrimp, Backswimmers, aquatic beetles, aquatic insect larvae, tadpoles, toads, salamanders, Killdeer, and ducks.

conservation Branchinecta lynchi is listed as a Threatened species. It is found in the Central

Valley and a few places in the Coast Ranges where it occurs in only certain types of vernal pools. It may be threatened by extinction due to loss of its

vernal pool habitat through development and new agriculture. Linderiella occidentalis is the most common of California's vernal pool Fairy Shrimps.

investigate Linderiella occidentalis is the only species of Fairy Shrimp that has red eyes.

All other species have black eyes. See if you can find the red eyes on shrimp in the field.

Cysts versus eggs?

Birds, reptiles, fish and a number of other creatures produce eggs. An egg is a single cell enclosed in a hard or leathery shell. Development of the embryo (earliest life stage) does not take place until after the egg is laid. It takes weeks of perfect conditions for the embryo to fully develop and hatch.

Cysts are fully developed embryos enclosed in a hard, spongy shell. Fairy Shrimp and Tadpole Shrimp produce cysts instead of eggs. This is a great advantage when you live in a quickly disappearing habitat like a drying vernal pool. The embryo can hatch out of its shell as soon as there is water in the vernal pool.

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common name Seed Shrimp

scientific name

many different vernal pool species, few with names


Arthropoda Crustacea Ostracoda Podocopida

habitat vernal pools and freshwater marshes

size 0.1 mm to 0.5 cm long

description Many different species of Seed Shrimp live in vernal pools. They come in many

colors. They have a single eye. The body of a Seed Shrimp is protected by two shells that form its carapace. The carapace resembles a seed, so they are called Seed Shrimp. The body inside the carapace is short with two sections, a head and a thorax. The head has four pair of appendages (leg-like structures). The thorax has three more pair of appendages.

fun facts A common species of Seed Shrimp in Sacramento's vernal pools appears to be

green. However, its shell is actually clear. The green color comes from the algae that live on its shell. The algae ride around on the Seed Shrimp as they cruise the pool for food.

life cycle When a vernal pool fills with water, the cysts of Seed Shrimp hatch. Out pops a

larva from each cyst. The larva has a great big eye spot and looks nothing like the adult. When it is done growing, the larva metamorphoses into the adult form.

Seed Shrimp that live in shallow vernal pools must grow up quickly to reproduce before the pool dries. If their vernal pool suddenly begins to dry up, they quickly enter a kind of hibernation. They tightly shut their carapaces and wait for rain to refill the pool. They cannot hibernate through the whole summer though!

Seed Shrimp that live in deep vernal pools have more time to grow up. The water in deep pools can last for months. This gives the Seed Shrimp time to

mature and produce more generations of Seed Shrimp during a single wet phase. Like Water Fleas, female Seed Shrimp can make many daughters that are exact copies of themselves without mating! This is a neat trick called parthenogenesis.

When vernal pools start to evaporate and the water gets warm, Seed Shrimp (like Water Fleas) mate and produce a special cyst that can survive on the bottom of a vernal pool during the long, hot summer. Some of the cysts will hatch next year. Others will not hatch for many years, waiting for just the right conditions.

ecology Seed Shrimp are usually one of the most abundant crustaceans in a vernal pool.

They live mostly at the bottom of the vernal pools. Most of their food comes from the zone where the water meets the bottom. They are filter feeders like Fairy Shrimp, Clam Shrimp, and Water Fleas. They sweep Bacteria, Algae, Protozoa, and small particles of detritus into their mouths with the fine hairs on their appendages. Seed Shrimp are eaten by Tadpole Shrimp, Water Mites, Mallards and other ducks, as well as wading birds such as the Great Egret.

investigate • When you visit vernal pools, look for a species of green Seed Shrimp the size

of the dot at the beginning of this paragraph. Would you expect to find more Seed Shrimp in a sample of water collected from the surface of a vernal pool or from the bottom?

The larva of the Seed Shrimp looks a bit like the larva of a Water Flea. Check out the photo of a Water Flea larva on page 18 of your reading "The Three Phases of the Vernal Pool Ecosystem - The Wet Phase: Winter in the Vernal Pools".

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© Larry Serpa

common name

Vernal Pool Tadpole Shrimp

scientific name Lepidurus packardi


Arthropoda Crustacea Branchiopoda Notostraca

habitat vernal pools

size up to 5 cm long description Vernal Pool Tadpole Shrimp have a shield-like cover called a carapace. They

can be mottled olive-green, brown or gray. Their abdomen sticks out behind the carapace and ends in two long, thin tails. The endangered Vernal Pool Tadpole Shrimp has a short paddle between the tails. It's more common relative Triops does not.

fun facts Fossilized Tadpole Shrimp that lived millions of years ago look almost exactly

like the ones we see today. The shrimp lived on Earth before there were fish and they never evolved defenses against fish predators. So, like Fairy Shrimp, Tadpole Shrimp now can live only where fish do not – in temporary pools.

life cycle The eggs of Vernal Pool Tadpole Shrimp are drought-tolerant cysts. When

winter rains fill vernal pools and swales, some of the cysts will hatch. Others may not hatch for many years. As the Vernal Pool Tadpole Shrimp grows it sheds its carapace whenever it gets too small. Tadpole Shrimp are large (about the size of a half dollar coin). It takes them weeks to mature, so they tend to live in deeper vernal pools which last longer.

Female Tadpole Shrimp produce hundreds of encysted eggs which are deposited in the mud of the pool bottom. The cysts will rest there as the vernal pool evaporates and the bottom becomes hot and dry. The cysts can last for more than 10 years, until conditions are right to hatch.

ecology Vernal Pool Tadpole Shrimp are one of the largest invertebrate morsels an

animal can find for dinner in a vernal pool. They are eaten by wading birds such as egrets and herons and migratory waterfowl including ducks. Frogs eat them too. Bullfrogs (a non-native frog) can come from their breeding areas in

nearby permanent water (streams, lakes, and wetlands) to eat the Tadpole Shrimp.

Vernal Pool Tadpole Shrimp burrow or creep along the muddy bottom of the vernal pools. They eat (and swim) by beating their leaf-like feet in a wavelike motion from front to back. They catch food with the feet. Their feet then move food up a groove that runs up the middle of their underside toward their mouth. They are very aggressive omnivores. They eat algae, bacteria, protozoa, rotifers, aquatic earthworms, insects, Fairy Shrimp, frog eggs and tadpoles.

conservation The Vernal Pool Tadpole Shrimp is listed as an endangered species. It is

restricted to the Central Valley and the San Francisco Bay area. It occurs only in certain vernal pools. Due to its very limited range and the continuing loss of vernal pools due to new development and agriculture, Vernal Pool Tadpole Shrimp are Endangered. A species is listed as endangered when protection is needed to prevent the species from becoming extinct in the near future.

investigate Most vernal pools do not have Vernal Pool Tadpole Shrimp living in them.

What are some of the characteristics of vernal pools where you find Vernal Pool Tadpole Shrimp? Can you think of any reasons why the Lepidurus packardi would prefer such pools?

What's in a name?

Ever wonder why scientists bother to assign a unique scientific name to each species? Why not just use a common name that's easier to say and understand than Latin? Well, here's an example of the problems with common names:

- Few people know about the endangered Tadpole Shrimp species which lives in vernal pools. Rice farmers think that the Tadpole Shrimp is a common animal and a pest in their rice fields because the shrimp eat their rice. They'd think you were crazy wanting to save Tadpole Shrimp from extinction!

- It turns out that two different species share the same common name "Tadpole Shrimp." One species is a summer pest in rice fields. It's scientific name is Triops longicaudatus. When we call the pest species Triops longicaudatus and the endangered species Lepidurus packardi, the confusion is avoided. People who speak different languages can even understand one another if they all use the scientific name.

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common name Water Flea

scientific name

Simocephalus, Daphnia and other unnamed species


Arthropoda Crustacea Branchiopoda Cladocera

habitat vernal pools, lakes, ponds and wetlands

size 0.2-3.0 mm

description A Water Flea swims in a jerky, hopping motion like a flea. A carapace (shell) covers most of its body. The carapace is hinged on one side. The other side is open to allow the Water Flea’s legs to move through the water to collect food and to swim. Some of the species in vernal pools are transparent (clear), while others are shades of brown. Scientists have not yet identified most of the species of Water Fleas in vernal pools. More than 80 percent of them still do not have names.

fun facts During most of the wet phase of a vernal pool, the Water Fleas are all female.

Each female can reproduce all by herself, without the help of a male. She produces fertile eggs and carries them in a brood pouch until they hatch. The brood pouch is like a knapsack that lies between her back and her carapace. It can hold up to 20 eggs. Sometimes the eggs get so heavy that the brood pouch tips the mother upside down! She swims upside down until the eggs hatch and she can release them into the water. All of her young are females that grow up

to be exact copies of the mother. This way of reproducing is called parthenogenesis.

life cycle All summer long, special Water Flea cysts called epiphia (pronounced e-PI-fee-

a) lie on the bottom of the vernal pool. These epiphia are adapted to survive many long, hot summers. When rainwater fills a vernal pool, the epiphia hatch into female Water Fleas. There are no males! As each female grows, her carapace becomes too small. She grows a new, larger carapace and sheds the old one. This process of growing and shedding is called molting.

As the vernal pool starts to dry up, the water gets warmer and there is less oxygen. These are signs that it is time for the Water Fleas to make epiphia. However, females cannot make epiphia without males. Almost like magic, about half of the female Water Fleas turn into males. They mate with the females. Instead of making young Water Fleas, the mated pair make two epiphia. The epiphia develop on the back of the female. They look like a dark brown saddle with two dark spots. When the epiphia mature, they fall to the bottom of the pool. Not all the epiphia will hatch the next winter. Some will stay on the bottom for many years, awaiting just the right conditions to make them hatch.

ecology Water Fleas are filter feeders. They collect detritus, Algae, Bacteria, and

Protozoa with their legs. The legs sweep the tiny particles of food into a food groove that leads to the mouth. Water Fleas are eaten by the fierce larvae of Damselflies and Aquatic Beetles (especially Dytiscid beetle larvae). Other major predators of Water Fleas are the Backswimmer, Water Boatman and the larvae of the Phantom Midge. The Phantom Midge larva has two floats and a special hook that is designed to catch Water Fleas!

investigate In vernal pools you will see some species of Water Fleas that only live in vernal

pools. Other species of Water Fleas live in other wetlands, ponds and even roadside ditches (in the winter). You can easily collect Water Fleas from these other locations. It is fun to watch them for awhile before you return them to their habitat.

To collect Water Fleas: First, put water from their habitat into a wide-mouthed container. Gently sweep a small, fine aquarium net through their habitat. (The fine nets are usually white, not green.) Put the net into the container of water and turn it inside-out to release the Water Fleas. You will probably find other species of aquatic critters that look like those in vernal pools. See how many you can identify using the Critter Catalog in your classroom or online at www.sacsplash.org.

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© Ken Davis

© David Rosen

common name Aquatic Beetles


phylum class order family

Arthropoda Insecta Coleoptera Dytiscidae and Hydrophilidae

habitat vernal pools, lakes, ponds, marshes, and quiet streams

size 3 to 44 mm long

description The most common species of Aquatic Beetles in vernal pools come from two families: The Predaceous Diving Beetles (the Dytiscids) and the Water Scavenger Beetles (the Hydrophilids). The larvae of both families are similar. They are worm-like, with hard heads and a pair of long, sharp pincers for jaws. Their jaws are specially designed to capture and eat aquatic animals. The jaws have long, hollow grooves along them that work like straws to suck out nutritious body fluids. The larvae of some species hunt by hanging by their tails from the water surface. Others hold onto underwater plants.

description (continued)

Adult beetles can fly. They can also swim on top of or under water. The hind legs are flat and fringed with long hairs that form paddles for swimming. The adult beetles are smooth, oval and very hard. Most are black, but some species are brown or green. Like other beetles, they have two pair of wings. The front pair is hardened to cover the back of the beetle. Tucked under these hard wings

is a pair of normal wings used for flying. The adults of many Aquatic Beetle species protect themselves with a sharp spine on the end of their abdomen, so watch out!

fun facts The larvae of Aquatic Beetles are called "Water Tigers" because they are fierce

hunters. They will eat almost any prey they can catch. The Ricksecker's Water Scavenger Beetle stabs its prey with its jaws. Then it climbs up a plant to get to the water surface where it holds its prey out of the water. The juices from the prey run into the beetle's mouth, without flowing into the vernal pool. This method avoids loss of the juices and avoids attracting other predators to lunch.

life cycle The female beetles lay their eggs under water. Most species deposit eggs in a

silk case that they attach to an aquatic plant. The eggs hatch into larvae, which are soft-bodied and worm-like. The larvae go through metamorphosis, to change into their adult beetle form.

ecology Many species of Aquatic Beetles live in vernal pools. The larvae will eat almost

anything that moves, including prey much larger than themselves. They eat Water Fleas, Flatworms, Copepods, Mosquito larvae, Water Boatmen, and Pacific Chorus Frog tadpoles. They will even eat the larvae of other Aquatic Beetles. As adults, Dytiscid beetles continue to be carnivores. Hydrophilid beetle adults become herbivores. The larvae and adults of Aquatic Beetles are eaten by frogs, salamanders, wading birds like the Great Blue Heron, shore birds like the Killdeer, and ducks like the Mallard.

investigate You will probably see Aquatic Beetle larvae in vernal pools. However, it is less

common to see the adults. Observe other common beetles that you can easily find in the field or around your home, such as Lady Bugs. Watch them just as they take off to fly. You will notice that the hardened wings (the elytra) are hinged at the top. The beetle opens this pair to allow the wings underneath to unfold and fly.

Aquatic insects

Dytiscid and Hydrophilid beetles are insects. About a million insect species have been discovered and researchers estimate that at least two million exist. The number of insect species on Earth is greater than the total of all other animal species combined.

Most insect species live on land. There are only about 20,000 species of insects that spend part or all of their lives in the water. That means that only 2% of insects live in aquatic environments! Most of them must have clean water environments to survive.

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© Ken Davis

common name

Dragonflies and Damselflies


phylum class order suborder

Arthropoda Insecta Odonata Anisoptera (Dragonflies) Zygoptera (Damselflies)

habitat all freshwater wetlands including lakes, ponds, marshes, streams, rivers and vernal pools

size 2.2 to 8.0 cm long (adults)

description The adult Dragonfly has a long narrow body. It holds its wings out to its sides

when perched. Dragonflies also have very large eyes that touch each other in the center. Different species may be different colors: red, green, blue or brown.

The adult Damselfly is similar, but holds its wings together over its back (like a butterfly) when perched. Its eyes do not meet in the middle of its head. Damselflies are also much smaller than Dragonflies. The Damselflies at Mather Field are usually blue or blue-green.

Both Dragonfly and Damselfly larvae are aquatic. The larvae have large eyes similar to the adults. The Damselfly larva has a long narrow body with three feather-like tails which are its gills. The Dragonfly larva has a fatter body and no external gills.

fun facts Dragonflies are one of the most ancient of the flying insects. There are fossil

records of Dragonflies from before the dinosaurs. Some of the fossil Dragonflies have wingspans of 32 cm (wider than a frisbee!). Dragonflies are now smaller, but have changed very little since prehistoric times.

life cycle The female Dragonflies and Damselflies lay their eggs in the water. The

Dragonfly lays its eggs directly in the water. The Damselfly inserts its eggs in underwater vegetation. The eggs hatch within a few days and the larvae grow quickly.

Each larva molts 8 to 16 times during its growth. When a larva molts, it sheds its old, too-tight skin. Underneath is a new, larger skin into which it can grow. From the last molt, an adult emerges. Unlike butterflies, there is no pupal stage between larva and adult. The newly emerged adult is fragile and very shiny. It takes a day or two for its skin and wings to harden.

ecology The larvae of the Dragonfly and Damselfly are predators. They eat many of the

critters that occupy vernal pools including Mosquito larva, tadpoles, Fairy Shrimp, Tadpole Shrimp, and many others. They have special mouth parts which allow them to grab any prey that swims into view. The larvae are eaten by wading birds and fish.

Adult Dragonflies and Damselflies are also predators. They eat flying insects of all types. One of the common names for the Dragonfly is Mosquito Hawk referring to its hunting of Mosquitoes. The adults are eaten by birds and spiders.

conservation The larvae of Dragonflies and Damselflies are one of the signs of a healthy

aquatic ecosystem. They show that the food web is intact and functioning. The presence of adults near water is also a good indication of a healthy ecosystem. When the adults or larvae are absent, it usually means that the habitat is polluted.

investigate Some species of Dragonflies sit on a perch waiting for a meal to fly close. They

then fly off the perch to catch the insect and immediately return to the same perch. This behavior is similar to that shown by birds known as flycatchers. Watch for Dragonflies with this behavior at Mather Field.

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© David Rosen

common name Mosquito

scientific name several different species


Arthropoda Insecta Diptera Culicidae

habitat larvae live in still water

size larvae 5 to 13 mm, adults 1 to 1.5 cm

description Adult Mosquitoes are gray or black and have two scaly wings. Females have a long, straw-like mouth for sucking blood. Males look different, with feathery antennae and mouthparts that cannot pierce skin. Mosquito larvae are brown, black or gray and have a breathing tube on their tail.

fun facts When a female Mosquito is ready to lay her eggs, she searches for stagnant

(still) water with plenty of rotting detritus and bacteria for her larvae to eat. Her antennae can smell the gas that the bacteria make when they decompose detritus. More gas means more food for her young!

life cycle The Mosquito goes through four stages during its life cycle: egg, larva, pupa,

and adult. The eggs normally hatch into larvae within 48 hours. Larvae must live in water from 7 to 14 days depending on the water temperature. During this time, the larva molts 3 times and grows to almost 1 cm. After the larva molts the fourth time it becomes a pupa. The pupa is lighter than the water and floats on the surface. The pupa does not eat. In 1 to 4 days, the adult Mosquito comes out of the pupa. It rests on the surface of the water until its body dries and hardens enough to fly away.

ecology A female Mosquito rarely lays her eggs in the clean water of a vernal pool. In a

healthy vernal pool her larvae would have to compete with many vernal pool

critters for food. So the female Mosquito lays her eggs in stagnant waters, such as roadside ditches, wetlands, and even buckets of water in your backyard. Here the larvae find plenty of Algae, detritus, Bacteria and Protozoa to eat. In vernal pools, Mosquito larvae are eaten by aquatic insect larvae such as the larvae of Dragonflies and Damselflies.

Adult female Mosquitoes feed on the blood of birds, lizards, people and other mammals. They need the protein found in blood to develop healthy eggs. Male Mosquitoes do not lay eggs, so they do not need blood. They feed on the nectar of flowers. In vernal pool grasslands, bats, spiders, Dragonflies, Damselflies, Killdeer, and other birds eat Mosquitoes.

When a vernal pool is polluted, more Mosquito larvae occur in it. This is a sign that the food web has been disrupted. When urban runoff kills aquatic critters, it leaves more detritus, Bacteria, and Protozoa for Mosquito larvae to eat.

investigate West Nile Virus is a serious disease spread by some species of Mosquitoes.

Fear about the disease can lead communities to spray pesticides over vernal pool grasslands, even though the Mosquitoes that carry West Nile Virus do not lay eggs in vernal pools. Even worse, pesticides can kill many other vernal pool species as well. Could spraying vernal pool grasslands actually lead to more Mosquitoes in vernal pools? How?

Water has a tight surface, like a very thin balloon. It is called surface tension. Mosquito larvae hang from it. Few aquatic critters can breathe without it. If oil or soap gets into runoff, the surface tension of water is destroyed. This kills most aquatic species. You can see this effect with Mosquito larvae. Find some larvae in a container of water (and detritus) that has been sitting outside for a few weeks. Break the water's surface tension by stirring the water. Watch what the larvae do. Add 4 to 8 drops of dish soap (or cooking oil) to the surface. Watch what happens. Pour out the water so the Mosquitoes don't hatch.

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© Ken Davis

common name Solitary Bees

scientific name

Andrena spp. Panurginus spp.


Arthropoda Insecta Hymenoptera Andrenidae

habitat grasslands and vernal pools

size 6-15 mm long

description These are small bees, often mistaken for a fly if not observed closely. They are

black or dark gray, sometimes with gray hairs on the face and head. Solitary Bees have hairs at the middle joint of their hind legs which form baskets in which they carry pollen.

life cycle Solitary Bees emerge in the spring when their host flowers are blooming. After

mating, the female Solitary Bee digs a nest. The nest begins with a tunnel straight down into the ground for a few inches. From the main entrance tunnel, she digs a side tunnel which ends in a chamber. This brood chamber is about 1 cm wide and 2 cm tall. The inside of the chamber is polished by the bee and coated with a waxy substance.

Once the brood chamber is complete, the female bee begins to collect pollen and nectar from the host flowers. These are brought to the brood chamber and slowly formed into a ball about 6-8 mm across. The female solitary bee deposits a single egg on the pollen ball. Then she seals up the brood chamber and proceeds to dig another side tunnel and new brood chamber. A single female may dig 8-10 chambers.

The egg hatches pretty quickly and the bee larva proceeds to eat all of the pollen ball. It then rests for a while. In the autumn, the larva changes into an adult. The adult bee then spends the winter just sitting in its chamber. It emerges the following spring when its host plant is again in flower.

The male Solitary Bee hangs out at the flowers hoping to mate with more females and does not help with digging the nest or collecting pollen.

fun facts In years of drought vernal pools might not fill with rainwater and flowers do

not bloom. Do the Solitary Bee species die out because they cannot reproduce without their host plants? Researchers at the University of California at Davis have discovered that vernal pool Solitary Bees can remain underground for up to four years, waiting for the 2-3 weeks when their host plant is in bloom. How they know when the flowers are blooming, when they are still sealed in their underground brood chambers, is yet another mystery of the vernal pools.

ecology Solitary Bees generally visit only a single species or closely related plants in the

same genus. At Mather Field, several groups of flowers are visited by Solitary Bees including Goldfields, Meadowfoam, and Downingia. The bees that visit Goldfields are a different species than those that visit Meadowfoam or Downingia. In addition to gathering pollen and nectar for their offspring, the Solitary Bees help to pollinate the flowers that they visit. Solitary Bees are eaten by spiders and other insects.

conservation Solitary Bees dig their nests in the upland soils next to vernal pools. They also

rely on the vernal pool plants to provide the pollen and nectar to feed their young. When we protect vernal pools in order to conserve their plant and animal species, we need to also protect the nearby grasslands for species like Solitary Bees.

investigate Solitary Bees can be seen flying over masses of flowers. When you spot some,

try to tell which flowers they are visiting by the color of the pollen in their pollen baskets.

What are Bees?

When most people mention "bees" they are referring to the Honey Bees. Honey Bees were introduced from the Old World to produce honey and pollinate crops. There are over 1,000 species of native bees in California. Like wasps, most of these are solitary and dig nests in the ground. Only Honey Bees and bumble bees are social and live together in hives. All bees collect pollen to feed their larvae.

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© Nova Scotia Museum of Natural History Website

common name Bullfrog

scientific names Rana catesbeiana


Chordata Amphibia Anura Ranidae

habitat ponds and streams with deep, slowly moving water

size 15 to 25 cm for adults, and up to 15 cm for tadpoles

description The Bullfrog is a large green or brownish-green frog with long, strong legs for

jumping. This frog usually has dark spots on its back and hind legs. Bullfrog males have a bright yellow throat, and all Bullfrogs have large, exposed eardrums on the sides of their heads.

fun facts At night, the Bullfrog makes an impressive sound. It bellows out in a loud, low

voice, which sounds like "aarooom." Many people have been startled by its alarm call, which is a sharp, loud squeak. The frog makes this sound when it jumps from the pond edge into the water. When captured, adult Bullfrogs often relax their bodies and play dead. When released, they quickly jump away.

life cycle Female Bullfrogs deposit many thousands of eggs in large masses. The tadpoles

require at least six months to transform into frogs. In many areas, they spend the winter as tadpoles and do not transform until their second year.

ecology Bullfrogs are native to the eastern United States, but they were introduced into

California late in the 1800's. They are now common in ponds and streams with deep, slowly moving water. While they cannot spend the entire year in temporary wetlands, these frogs sometimes spend the spring in the vernal pools.

The Bullfrog was brought to California as a source of food for people. Since it was introduced, the Bullfrog has hurt California's wetlands and native species. Bullfrogs eat many animals. Some of them are as big as the Bullfrog itself! Worms, insects, spiders, crayfish, salamanders, other frogs, fish, lizards, snakes, turtles, mice, bats, and birds are all prey for hungry Bullfrogs. Scientists think that the Bullfrog's large appetite may be responsible for the a decrease in

the number of California's native frogs and fishes. The Bullfrog is food for many animals including snakes, large wading birds, predatory fish, and mammals (including humans).

conservation There is no effort to protect Bullfrogs because they are a pest species. It is legal

to hunt Bullfrogs in the State of California. People sometimes hunt the frogs for their legs. There are many recipes for cooking frog's legs. People say they taste like chicken.

investigate Which species in the vernal pool grassland could be affected if Bullfrogs found

their way into a vernal pool? Remember to consider the species that Bullfrogs eat, as well as the native species that are connected to those species through the food web.

Think about Introduced Species

Is it a good idea to bring wild animals from other parts of the country to California? How might this affect the animals and plants that live here naturally? Can you name some species of plants in the grasslands that are not native to California?

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© David Rosen

common name Pacific Chorus Frog

scientific names Pseudacris regilla


Chordata Amphibia Anura Ranidae

habitat vernal pool grasslands, ponds and other still waters

size 1.5 to 5.0 cm

description The Pacific Chorus Frog is the only green or brown frog in our area with a dark

"mask" across its eyes and "suction cups" on its toes. Often called the Pacific Treefrog, it uses these toe pads to help climb plants, trees, even walls and windows!

fun facts The call of the Pacific Chorus Frog is often heard during spring and summer

evenings. Males make a "ri-bett," or "kreck-ek" sound when calling for females.On some evenings, wetland areas can be almost deafening with the sound of thousands of these frogs trying to "out sing" each other. This sound is often recorded and used in movies during night scenes.

life cycle The Pacific Chorus Frog lays its eggs in vernal pools and other still water. The

eggs hatch into tadpoles within 2 to 5 weeks. This frog even breeds in empty buckets and old, discarded tires! The tadpoles metamorphose into small frogs in one or two months. The tadpoles are a favorite food of the fierce Water Tigers (the aquatic larvae of Water Scavenger Beetles).

ecology Pacific Chorus Frogs are the most common frog in the Sacramento area. These

frogs are an important part of wetland communities. Because they are so common, they provide food for many other animals, including raccoons, snakes, wading birds, ducks and even other frog species. The tadpoles eat Algae, detritus, Bacteria, Protozoa, Rotifers and small crustaceans. The adult frogs eat slugs, spiders, centipedes, and insects.

investigate As you're walking through the vernal pool grasslands, listen for the distinctive call of the Pacific Chorus Frog. You will probably hear it several times. In early spring, egg clusters may be present in the water. Look carefully (without disturbing the water) for small, golf ball-sized clusters of clear eggs. They will be attached to sticks or plants. In spring and early summer, look for tadpoles at the water's edge. Why are they all grouped together at the edge of the water? Where do you think the young frogs go when the water dries up?

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© David Rosen

common name Western Spadefoot

scientific names Spea hammondii


Chordata Amphibia Anura Pelobatidae

habitat vernal pool grasslands and some cattle ponds

size 4 to 6 cm for adults

description The Western Spadefoot is small and squat. Its back is olive-brown or gray with

dark blotches and little red bumps. The skin on its back is mostly smooth, unlike that of the warty Western Toad. The adult Spadefoot has a white belly.

It has eyes like a cat - the pupils are vertical, black, and almond-shaped. The Spadefoot gets its name from the tiny black shovels (spades) on its hind feet. It uses these shovels to dig burrows in the ground.

fun facts The male Spadefoot makes a sound like a tiny snore to call females to the

breeding pool. On a quiet, windless night a group of male Spadefoots can be heard almost a mile away. The females are usually silent.

When injured or handled roughly, the Spadefoot gives off a smell like roasted peanuts or garlic, which can cause sneezing.

life cycle Spadefoots gather at vernal pools to breed in early spring, after winter rains fill

the pools. Females lay several hundred eggs. The eggs are covered in clear jelly and are laid in small clusters of thirty eggs or less. The egg clusters are usually laid on plants, just below the surface of the water. The eggs hatch in 3 or 4 days if the water is warm. If the water is cooler, they eggs can take a week to hatch.

The newly hatched tadpoles stay close to the egg cluster for the first few days. It takes them 5 to 6 weeks to grow about two inches. After about 8 weeks the tadpoles change into young Spadefoots. This change is called metamorphosis. During metamorphosis a Spadefoot cannot eat. After metamorphosis, a young

Spadefoot is much smaller than the tadpole from which it came. A Spadefoot takes about two years to become an adult. An adult can live for several years.

ecology Western Spadefoots are only active on a few rainy nights between October and

March. On these nights, they leave their burrows to travel to breeding pools and to hunt. Adults eat mostly insects, especially beetles, moths, and moth larvae (caterpillars). Adults do not have many predators because their skin tastes nasty. Small mammals sometimes eat Spadefoots that have been killed on roads, but they leave the skin untouched. Bullfrogs, on the other hand, have been known to swallow adult Spadefoots whole!

Unlike the adults, Spadefoot tadpoles are not protected by skin poison. The tadpoles are eaten by Aquatic Beetle larvae and other aquatic insect larvae, California Tiger Salamander larvae, wading birds and ducks. Spadefoot tadpoles are omnivores, which means they eat both plants and animals. They eat detritus, Bacteria, Protozoa, small crustaceans and sometimes they even eat each other!

conservation Spadefoots are very picky about their habitat. They only live in certain vernal

pools and in some drinking ponds used by cattle. Scientists do not understand why they breed in some pools and not in others. When their breeding pools are destroyed, they often have nowhere else to go. To protect Spadefoots for the future, we will have to protect the vernal pool grasslands where they live today.

investigate Why do you think the biggest Western Spadefoots come from pools where

California Tiger Salamander larvae are present? Talk to the California Tiger Salamander specialist in your class to work on your answer.

What's in a name?

Spea, the genus of the Western Spadefoot, means "cave", which refers to its habit of spending its adult life in burrows.

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© David Rosen

common name

California Tiger Salamander

scientific names

Ambystoma tigrinum californiense

class order family

Amphibia Caudata Ambystomatidae

habitat ponds, streams, and large, cloudy vernal pools (over 250 square feet) without fish

size 18 to 38 cm description The most remarkable feature of the California Tiger Salamander is its striking

coloration. Adults are black with yellow or cream spots. The body is thick, with a rounded nose and a pudgy tail. Larvae are pale and have no spots. The larvae also have large fins on the back and feathery gills.

fun facts Adult California Tiger Salamanders can live as long as 30 or maybe even 40

years! Both Tiger Salamanders and Western Spadefoots reproduce in large, deep vernal pools. However, in pools with California Tiger Salamanders you will not find many Western Spadefoots. The few Spadefoots that live there are very large. Why do you think this is true?

life cycle California Tiger Salamanders spend the summer underground in rodent

burrows. After the first few heavy rains in November, they come out of their burrows and migrate to breeding pools, such as large vernal pools and stock ponds (cattle watering holes). The breeding season lasts from December through February. During this time females lay small clusters of eggs on twigs, grass stems, and plants. A jelly-like substance coats the eggs. This protects the eggs against temperature extremes and destruction. Yellowish gray larvae hatch from the eggs 2 to 4 weeks later.

ecology Small larvae feed on microscopic organisms. Larger larvae also feed on tiny

Western Spadefoot tadpoles, Rotifers, crustaceans and aquatic insect larvae. Adult California Tiger Salamanders use a sit-and-wait strategy to prey on earthworms, snails, insects, fish, Western Spadefoots, and small mammals. In

the few habitats where they remain, California Tiger Salamanders are eaten by Great Egrets, Great Blue Herons, fish and introduced (non-native) Bullfrogs.

conservation The California Tiger Salamander is threatened by habitat loss. Most of the loss

is due to urban development, farming, and predation by introduced Bullfrogs and fish in breeding ponds. They are also killed by cars on roads that cross their migratory routes.

investigate You will not see any California Tiger Salamanders at the Mather Field vernal

pools. Why do think they do not live there?

You can find California Tiger Salamanders at Olcott Lake, a huge vernal pool at Jepson Prairie near Dixon, California. This is less than one hour from Sacramento. During March and April, you can tour Olcott Lake and other vernal pools with the Jepson Prairie Docents and see the salamanders.

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Jens V. Vindum, © California Academy of Science

common name California Kingsnake

scientific names

Lampropeltis getulus californiae


Chordata Reptilia Squamata Colubridae

habitat grasslands, freshwater marshes, desert, farmland, chaparral, forest, and woodland

size 27 to 76 cm description The California Kingsnake is dark brown or black with whitish-yellow bands. fun facts The Kingsnake received its name because it often eats other snakes. It is

famous for eating Rattlesnakes. When a hungry Kingsnake finds a Rattlesnake, it will bite the Rattlesnake behind the head and coil itself around the body. The Kingsnake is nearly immune to Rattlesnake venom and does not worry about being bitten. Like a Boa Constrictor, the Kingsnake tightens the coils around the Rattlesnake and suffocates it. Sometimes the Kingsnake will eat the Rattlesnake before it is dead.

life cycle In June or July, the female California Kingsnake lays 2 to 24 eggs under leaves

on the ground. She leaves the eggs after laying them. About 70 days later, the baby snakes emerge. They are 20 to 33 centimeters and look like miniature adult snakes.

ecology Kingsnakes eat lizards, snakes, mice, birds, and bird eggs. California

Kingsnakes have even been known to eat their own shed skins! The Kingsnake is eaten by hawks, owls, coyotes, opossums, skunks, and other predators.

conservation Some people kill snakes because they are afraid that the snakes might hurt

them. They do not realize that the snakes are even more afraid of humans than we are of them! Kingsnakes, like many snakes, play an important role in controlling rodent populations. What are some of the rodents living at Mather Field?

investigate California Kingsnakes have been found in the grasslands at Mather Field but they are not common. It is exciting to see them because they are so beautifully colored. What would be some effects on the food web if people kill every snake they see? If there were no Kingsnakes, what poisonous snake population might increase?

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© Ken Davis

common name Garter Snakes

scientific names

Thamnophis sirtalis sirtalis (Common Garter Snake) Thamnophis elegans elegans (Western Terrestrial Garter Snake)



habitat vernal pool grasslands and many other habitats, often near water

size 0.46 to 1.3 meters

description The Common (or Valley) Garter Snake is easily identifiable by a black body,

yellow stripes down the back, and red blotches on the sides. The Western Terrestrial Garter Snake has a black or dark gray back with a dull yellow stripe down the middle. The dark background color has tiny white spots, which can be hard to see.

fun facts When handled or otherwise disturbed, Garter Snakes usually release a stinky-

smelling musk. life cycle During the winter, Garter Snakes hibernate under rocks and rotting logs, and in

rodent burrows. They select mates in the spring after they come out of hibernation. In July, seven to thirty young are born live.

ecology Garter Snakes feed on many different animals, including fish, frogs, toads,

salamanders, insects, and earthworms. They are excellent swimmers and are usually found close to some source of water. They are eaten by a variety of mammals, birds and other snakes.

conservation Some people kill snakes because they are afraid that the snakes might hurt

them. They do not realize that the snakes are even more afraid of humans than we are of them! Garter Snakes, like many snakes, play an important role in controlling populations of rodents. Rodents are a group of mammals that includes mice, pocket gophers, voles, ground squirrels and other species.

investigate Garter Snakes are one of the most common snakes at Mather Field. With luck (and quiet movement) you may see one slithering through the grass as you approach. If you inspect the ground you will see how much habitat is created for snakes by the burrowing rodents in the vernal pools and grasslands. The burrows of the California Vole and Botta’s Pocket Gopher are everywhere and they are great places for snakes to seek protection from sun, cold, predators and you! Many of their prey hide in those same underground shelters.

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unknown photographer, © California Academy of Science

common name Gopher Snake

scientific names Pituophis melanoleucus



habitat grasslands, farm fields and brush fields

size 0.8 to 1.8 meters

description The Gopher Snake is yellowish brown, with dark, diamond-shaped markings.

They can grow very large, often over 2 meters in length.. fun facts When disturbed or attacked by a predator, a Gopher Snake will often flatten its

head (making it look wider), hiss loudly, and shake its tail very fast. What kind of snake do you think it might be trying to imitate?

life cycle Female Gopher Snakes lay between 3-18 eggs (usually 7 or 8) in the early

summer. Eggs are usually laid below ground in mammal burrows or moist, loose soil. Baby snakes emerge in the fall..

ecology The Gopher Snake is very common in California and can be found in many

habitat types. Like the California Kingsnake, the Gopher Snake is a constrictor, which squeezes its prey in order to kill it. They feed on mammals, birds, and occasionally lizards.

Gopher Snakes, like many other snakes, play an important role in controlling rodent populations. Rodents are mammals such as voles, pocket gophers, ground squirrels and mice. Think about the effects on the vernal pool grassland food web if the number of Gopher Snakes became much smaller?

conservation Some people kill snakes out of ignorance because they think snakes are bad or

they are afraid that the snakes might hurt them. They do not realize that snakes are even more afraid of humans than we are of them! Although some snakes will strike if they feel threatened, they tend to slither away when they feel the vibration of our footsteps coming toward them. To avoid scaring a snake, all

you have to do is make sure they know you are coming. They should be left alone, unharmed.

investigate Because they look similar, Gopher Snakes are often mistaken for Rattlesnakes.

Using a reptile field guide, other books or a search of the Internet, find a photograph or drawing of a species of rattlesnake that lives in our area. Compare its appearance to that of a Gopher Snake. Would you be fooled by the Gopher Snake’s disguise?

Discuss the Gopher Snake with a classmate who is studying the California Kingsnake. Do you think the Kingsnake would be afraid to eat a Gopher Snake? Why?

©


Dr. Lloyd Glenn Ingles,

© California Academy of Sciences

common name Coyote

scientific name Canis latrans


Chordata Mammalia Carnivora Canidae

habitat most common in grasslands, sagebrush, and deserts; also found in chaparral and forests

size up to 94 cm long, plus a 28-40 cm tail

description The Coyote is gray with reddish-gray legs, feet and ears and a whitish belly. Its

tail is bushier and nose more pointed than most dogs. It makes high-pitched "yaps" and "whinnies" in the evenings and early mornings.

fun facts The Coyote relies on its keen senses for hunting. The Coyote can hear voles or

gophers moving around in their underground tunnels. It can dig so fast that it can sometimes corner the vole or gopher in a dead-end tunnel. In colder areas Coyotes can even hear voles moving under the snow. The Coyote drives its head into the snow at just the right place to clamp its jaws upon the unsuspecting vole.

life cycle Female Coyotes breed once per year, starting when they are 2 years old. They

give birth to 5 to 10 pups during April or May. These young are born and raised in a den dug deep into the ground, or in natural caves or hollow trees. In 6 to 9 months the pups are ready to live on their own.

ecology The Coyote is somewhere between an omnivore and a carnivore. It hunts

rabbits, voles, mice, and gophers. But it also eats berries, grass, and other plant materials that it happens to find. Coyotes are at the top of the food web.

conservation Coyotes can live for 15 years. However, more than half the Coyotes born never

reach adulthood. Most of these deaths result from Coyote control programs. Some farmers, ranchers, hunters and government agencies have long poisoned, trapped and shot the Coyote. Coyotes do kill some sheep and goats, but

probably killing so many Coyotes is unwise. What effects might the killing of so many Coyotes have on its food web?

investigate You can find the scat of Coyotes lying on the pavement of roads in the

grasslands at Mather Field. The Coyotes leave their scat where it is clearly seen and smelled, to mark their territory and keep other Coyotes away.

Coyotes may appear to be at the top of the food web, but consider that Coyotes are not large animals during their whole life. Coyote pups are small when young. What animals in the vernal pool ecosystem might prey on Coyote pups?

©


© Ken Davis

common name Black-tailed Jackrabbit

scientific name Lepus californicus


Chordata Mammalia Lagomorpha Leporidae

habitat common in grasslands and deserts

size up to 53 cm long

description The Black-tailed Jackrabbit is grayish-brown with large, black-tipped ears and a black streak on the top of its tail. Its long hind legs help it to run 30 to 35 mile per hour.

fun facts The Black-tailed Jackrabbit has an unusual habit: it eats its own feces! After

food is digested for the first time, the rabbit eats its "cecal" pellets. These pass through the jackrabbit’s digestive system a second time to produce "fecal" pellets. This habit (called coprophagy) allows the Black-tailed Jackrabbit to take more energy and nutrients out of its food the second time around.

life cycle The female Black-tailed Jackrabbit gives birth to several litters between

December and September. There are 2 to 4 young per litter. The nest is a shallow depression on the ground. The newborn rabbits are covered with fur with eyes wide open, ready to run. If they do not become dinner for another species, Black-tailed Jackrabbits can live for 8 years.

ecology The Black-tailed Jackrabbit eats plants, so it is an herbivore. It sits at the base

of bushes or clumps of tall grasses, often near soil mounds piled up by Ground Squirrels or Pocket Gophers. These areas offer cover from the Golden Eagles, hawks and Coyotes which hunt them.

conservation The Black-tailed Jackrabbit once lived in large numbers in areas that have since

been turned into farms, houses and businesses. The way people live in an area changes the quality of its habitat so the jackrabbit can no longer survive there.

Some ranchers shoot and poison Black-tailed Jackrabbits. They believe that the rabbits compete with their cattle for food in the grasslands.

investigate While walking in grasslands, look for the round, dark brown, fecal pellets

dropped by the Black-tailed Jackrabbit. Look for the well-worn trails, about the width of a jackrabbit, that crisscross the grassland. Also, scan the horizon for two big ears sticking straight up into the air like antennae. Where there is one Black-tailed Jackrabbit, there are usually more!

©


© Lee Dittmann. Used with permission.

common name Botta's Pocket Gopher

scientific name Thomomys bottae


Chordata Mammalia Rodentia Geomyidae

habitat common in grasslands, open fields, and forest openings

size up to 23 cm long excluding tail

description Botta's Pocket Gopher is tan to medium brown and often the color of the local

soil. The gopher uses its short, powerful front legs and neck to "swim" through soil and push it away. Its short tail is partly covered in short, coarse fur. It fills its fur-lined cheek pouches with food to carry it into storage chambers in its underground burrow system.

fun facts Botta's Pocket Gophers are very important because they make the soil richer.

They push minerals from the deeper parts of their burrows toward the surface. Their burrowing helps make richer soils by mixing air, water, plant parts, animal wastes, micro-organisms and minerals. Richer soil helps the gophers too, because it make plants grow bigger and faster, which makes more food for gophers to eat!

life cycle During the year, a female Botta's Pocket Gopher will have one to three litters

(batches of babies). Each litter has about four or five young. Although gophers can breed all year, most young are born during the spring and at the end of summer.

ecology Gophers make and live in closed burrow systems, a few inches to ten feet below

ground. Their burrows consist of a large den and connecting tunnels. A gopher burrow system can have 15 connected tunnels totaling 200 feet in length! In vernal pool grasslands they stay nearer the surface because the hardpan layer keeps them from digging deeper.

The Botta's Pocket Gopher is an herbivore. It eats roots, stems and bulbs of plants such as White Hyacinth, Vernal Pool Brodiaea and Field Cluster Lily.

The gopher can eat without leaving the safety of its underground burrow. It simply pulls its food into the tunnel through the roof! The Botta's Pocket Gopher rarely appears above ground during the day. When it does, a Red-tailed Hawk, Great Blue Heron or Great Egret could eat it. It can avoid most of its predators by leaving the burrow only at night. However, Coyotes and the Great Horned Owl are nocturnal (active at night) and welcome a meal of Botta's Pocket Gopher. Night or day, a California King Snake or Gopher Snake can crawl into a gopher burrow and eat both adults and young.

conservation Botta's Pocket Gopher cannot live where soils have been paved over or are

plowed up every year. The quality of its habitat is also decreasing because of Yellow Star-thistle, an invasive plant species from Asia. The Yellow Star-thistle is crowding out the native plant species that the gopher needs for food.

investigate Though you are unlikely to see gophers during the day, you will see plenty of

signs that they have been there. As you walk across the grassland, soft spots and lumps in the soil tell you that the gophers have been at work.

When they tunnel under vernal pools during the dry season, Botta's Pocket Gophers make their "gopher mounds" on the bottom of the pools. Visit the pools during the spring bloom and see what species of plants prefer to grow on the gopher mounds. In what ways do you think the gopher mounds and the pool bottom offer different conditions for plants to grow?

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Jack Kelly Clark, © University of California Regents

common name California Vole

scientific name Microtus californicus


Chordata Mammalia Rodentia Muridae

habitat common in grasslands, wetlands and wet meadows

size up to 14 cm long excluding tail description The California Vole is covered with grayish-brown fur. Its ears and legs are

short and it has pale feet. It has a cylindrical shape (like a toilet paper roll) with a tail that is 1/3 the length of the body.

fun facts California Voles make paths through the grasslands leading to the mouths of

their underground burrows. These surface "runways" are worn into the grass by daily travel. When chased by a predator, a vole can make a fast dash for the safety of its underground burrow using these cleared runways. If you walk quickly across the grassland you will often surprise a California Vole and see it scurry to its burrow.

life cycle California Voles reach maturity in one month. Female voles have litters of four

to eight young. In areas with abundant food and mild weather, each female can have up to five litters in a year.

ecology The California Vole can dig its own underground burrow system but it often

begins by using Pocket Gopher burrows. The tunnels are usually 1 to 5 meters long and up to one half meter below ground, with a nesting den somewhere inside. The ends of the burrows are left open. Many insects, spiders, centipedes, and other animals live in their burrows. Thus, the California Vole creates habitat for other species and the Pocket Gopher improves habitat for the vole.

The California Vole is mainly an herbivore. It eats grasses and other green plants and their seeds. It will sometimes eat bird eggs or other protein-rich food it can find easily. Voles are a major food source for hawks, owls, egrets, snakes, and coyotes. Weasels hunt voles by scurrying right into the vole's burrow

system. Weasels even live in the Vole's den chamber, after eating the resident vole!

conservation The California Vole can live in grasslands and fields that are not ploughed

every year, such as alfalfa and vineyards. It likes to visit sugar beets and vegetables that are large enough to provide cover from its predators. However the California Vole can cause damage to crops, so farmers sometimes poison them.

investigate Vole burrow openings are often worn bare and littered with fecal droppings.

You can sometimes find grass parts or flowers lying inside or near the burrow entrance. (Voles are sloppy eaters!) When a California Vole eats seeds on its "front porch", it often leaves the inedible husks of the seeds in a pile by the door. Such piles are called "middens". Look for midden piles in the grassland and see if you can tell what plant(s) the seeds came from. This will help you to find out more about the vole’s place in the food web.

©


© David Rosen

common name Great Blue Heron

scientific name Ardea herodias


Chordata Aves Ciconiiformes Ardeidae

habitat vernal pools, rivers and lakes

size 1.0 to 1.4 meters tall

description The Great Blue Heron is a wading bird. It has a blue-gray back, black patches

on its sides and a gray and white-striped belly. The cheeks, throat, and top of the head are white. It has a black stripe over its eye and a long, black feather decorating the back of its head. Its bill is yellow and its legs are greenish-brown.

fun facts The Great Blue Heron makes a sound like a loud, rusty squawk. The noise that

comes from a colony of nesting Great Blue Herons is very loud. What do you think is the advantage for the herons to nest in large colonies?

life cycle Great Blue Herons make nests and raise their young in areas called heronries. A

heronry is a group of trees where about 20-50 mating pairs build their nests. These nests may be reused year after year, if they are not destroyed by winter storms.

In March, the males arrive at the heronry and select a nest. Each male then performs his courtship display and the females choose their mates. Males and females commonly mate for life. After repairing the nest with reeds, grass and

moss, the female lays 3 to 5 pale blue eggs, about 5 cm in diameter. The male and female take turns sitting on the eggs for about 28 days.

When the hatchlings emerge, both parents feed them a diet of regurgitated (thrown up) food. Later, whole dead prey are dropped into the nest. A few weeks after hatching, the young begin to test their wings and fly short distances.The young grow quickly and are adult size by 42 days old. After 60 days, they leave the nest.

ecology Great Blue Herons wade in shallow water hunting for food. In vernal pool

grasslands, the Great Blue Heron eats many things including Clam Shrimp, Tadpole Shrimp, California Tiger Salamanders, Dragonfly and Damselfly larvae, snakes, Pocket Gophers, and the tadpoles and adults of the Western Toad, Pacific Chorus Frog and Western Spadefoot. Due to its large size, an adult Great Blue Heron has few predators. However, its young are less able to defend themselves. They are preyed upon by Red-tailed Hawks, eagles, ravens and raccoons.

conservation The California Department of Fish and Game has discovered that the heron

population is getting smaller. The Great Blue Heron is a "species of concern", meaning that it could become endangered if this trend continues.

The loss of herons is mostly due to habitat disturbance. People are constructing buildings in places near heronries. Herons are very sensitive to human presence around their nests. They will abandon eggs and young if they are disturbed. Another problem is the pollution of the marshes, lakes, and rivers where herons feed. If these water bodies are polluted, it can kill the Great Blue Heron’s prey. If the herons do not get enough to eat, they cannot survive.

investigate If you visit vernal pool grasslands when the pools are full of water, you are

likely to see a Great Blue Heron foraging (hunting) near the pools. Herons still come to the vernal pool grasslands after the water has evaporated in the spring when the pools are full of flowers. What critters do you think they are eating?

©


Dr/ Lloyd Glenn Ingles, © California Academy of Sciences

common name Great Egret

scientific name Casmerodius albus


Chordata Aves Ciconiiformes Ardeidae

habitat wetlands, ponds, shorelines, and wet fields

size 0.9 to 1.0 meters tall

description The Great Egret is a wading bird with white feathers. It has a long neck and

very long, black legs. Its bill is long, thick and yellow. An adult Great Egret is more than 3 feet tall.

fun facts During the late 1800's and the early 1900's, the Great Egret was hunted almost

to extinction. Its beautiful white plumes (feathers) were used to decorate ladies' hats. In 1903, Egret plumes were so popular they were worth twice their weight in gold! Millions of egrets, herons and other birds were killed every year just to decorate women's hats.

In the late 1880's two wealthy Boston women decided to put a stop to it. They invited all the well dressed ladies of the city to come to tea parties. They made them promise not to wear hats with bird feathers on them. This movement spread from women to men and from state to state. This was the start of the Audubon Society. Two hundred years later the Audubon Society is still hard at work to protect birds all around the world. You can join if you want to help!

life cycle The breeding season usually begins in mid-April. Great Egrets come to nesting

grounds called rookeries. Here they build nests of sticks and twigs in medium-sized trees. The male begins building the nest. He then brings materials to the female who finishes it. The mated pair often return to the same nest year after year. They repair or rebuild it as needed. The female lays 4 to 5 oval, blue-green eggs. The male and female take turns sitting on the nest for 23 to 24 days.

When the hatchlings emerge, they have white down (soft, small feathers) and pink bills. Both parents take care of the young. After about 3 weeks the young egrets start walking on branches near the nest. About 40 days after hatching, they begin to take short flights.

ecology During the day Great Egrets forage (hunt for food) alone or in small groups.

They forage in wetlands and other shallow waters or mud. They like the marshy shores of lakes and ponds, or slow moving streams. You will also see them in farmers' irrigation ditches and flooded cropland. In vernal pools, Great Egrets feed on Algae, Rotifers, Copepods, Seed Shrimp, Water Fleas, Aquatic Beetles, Aquatic Snails, Damselfly and Dragonfly larvae, the tadpoles and adults of Pacific Chorus Frogs, California Tiger Salamanders and Garter Snakes.

Great Egrets are at the top of the food web. Few predators want to attack such a large bird, with such a big beak! Great Egrets avoid most predators by roosting in tall trees at night with other egrets and herons. By nesting in large groups, thebirds can warn each other of predators. The young of Great Egrets are taken from their nests in rookeries by Raccoons, Great Horned Owls, Red-tailed Hawks and other hawks. Coyotes, Red-tailed Hawks and other hawks will also prey on Great Egrets while they are foraging.

investigate If you want to watch Great Egrets, visit their feeding habitats. Be sure to stay

away from rookeries. Egrets do not like visitors when they are nesting. You must move very slowly and quietly. The birds are very shy. They will fly away if you come too close. A pair of binoculars will help you see better without scaring them away.

April and May are good times to watch for Great Egrets at vernal pools. When big or deep vernal pools are drying up, Great Egrets fly in for a big meal. The larvae of Damselflies, Dragonflies, and Aquatic Beetles are large and abundant in big pools. There are also plenty of tadpoles and frogs, and Garter Snakes nearby to hunt them. When a Great Egret spots a Garter Snake, the hunter soon becomes the hunted. Imagine how a Great Egret gets a long snake down its longthroat!

Any easy way to see Great Egrets is to watch for them along the road. You will often see them in rice paddies, wet fields or ditches. See how many other species of wading birds you can find in the same places. What critters probably live in the water where you see Great Egrets foraging?

©


© Howard F. Towner

common name Mallard

scientific name Anas platyrhynchos


Chordata Aves Anseriformes Anatidae

habitat wetlands of all types

size 50-63 cm long description Mallards are medium sized ducks. The male and female have different color

patterns. The male has a shiny green head, a narrow white band around the neck, a brown chest, and gray sides. He also has a pair of curly feathers on his tail. The female is much plainer with spotted brown feathers. Both the male and female have a small blue patch on the wings.

There is a good reason for the female Mallard’s dull appearance—she will sit on the nest and guard the eggs. Her coloring blends with the surrounding reeds and grass, providing camouflage. Predators are less likely to see her and the nest that she sits on. If the predators cannot see the nest, they cannot attack it.

fun facts Mallards are the most common ducks in the Central Valley, particularly in

winter. Many live here year-round and others migrate here from the mountains and Great Basin in order to nest and raise their young. They live in many habitats including ponds, rivers, pastures, cropland, and parks.

life cycle From March through July, pairs of Mallards create nests near water in sparse

vegetation. After thoroughly lining the nest with down (soft, small feathers), the female lays 6 to 12 eggs. The female then sits on the eggs, keeping them warm and protected. After about 26 days, the eggs hatch and the female cares for the ducklings. The ducklings attempt their first flights 40 to 60 days after hatching.

ecology The Mallard's main diet is plants including grains, seeds and leaves. While

nesting, they also eat aquatic insects, snails, small crustaceans, earthworms and tadpoles. Mallard eggs and ducklings are eaten by many mammals, including striped skunks, rats, coyotes, raccoons and opossums. Adult Mallards are hunted by humans and occasionally other large predators.

investigate What other species of birds can you find in the vernal pool grassland which have colorful males and dull females? Some other birds you might investigate through classmates, books, or the Internet are Greater Yellow-legs, Red-winged Blackbird, Western Meadowlark and Killdeer.

©


© Ken Davis

common name Burrowing Owl

scientific name Athene cuncularia


Chordata Aves Strigiformes Strigidae

habitat grasslands, desert, farmland and shrubby fields

size 20 to 28 cm tall

description The Burrowing Owl is a small owl with very long legs and a short tail. The

throat is white. The body is grayish-brown and spotted with white and the round head has a white stripe above the eyes. Their eyes are bright yellow.

fun facts The male Burrowing Owl stands guard outside his burrow for weeks, protecting

his young. The sun bleaches his head feathers to a lighter color. By late summer, you can tell which owl is the male of a pair by his light-colored head.

life cycle The breeding season for Burrowing Owls begins in early March. After the

female lays 7 to 9 eggs, she and the male take turns sitting on them. Three to four weeks later, the eggs hatch and fluffy chicks emerge. One by one, the chicks grow braver, leaving the burrow and wandering outside the entrance. The parent owls stay close by, delivering live prey to the young to teach them to hunt and kill. The young leave the parent owls at the end of the summer. By then they have grown their adult feathers and can hunt alone.

ecology These owls live in underground burrows, lined with feathers, pellets, grass and

other objects. Despite their name, they usually do not dig their own burrows. They live in abandoned mammal burrows which they sometimes enlarge.

Burrowing Owls eat lots of insects, as well as ground squirrels, voles, mice, small birds, lizards and dead animals. They capture prey in many ways

including: diving from the air, gliding from a perch, and jumping on top of their prey from the ground. The main predators of Burrowing Owls are Swainson’s Hawks, Great Horned Owls, Coyotes, foxes and raccoons.

conservation Like many animals and plants, Burrowing Owls live in places where people

want to put houses and other development. Their habitat is disappearing quickly. Mammals like the ground squirrel dig the burrows where the owls live. However, some ranchers and farmers kill these mammals because they think of them as pests. This destruction of the mammals reduces habitat for the Burrowing Owl.

investigate There are only a few Burrowing Owls at Mather Field. You can tell if a burrow

has been used by owls because there will be small, white droppings around the entrance. Sometimes the owls decorate the entrance with things they have found. Always keep your distance from the burrows so you don’t scare the owls away.

©


© Ken Davis

common name Great Horned Owl

scientific name Bubo virginianus


Chordata Aves Strigiformes Strigidae

habitat grasslands, woods, mountain forests, desert canyons, chaparral, marshes and city parks


description The Great Horned Owl is a bulky bird, with a dark brown body and a white

throat. The brown body is marked with darker spots and stripes. The face is grayish around a pair of large, bright, yellow eyes. The head is decorated with two large tufts of feathers that look like horns.

fun facts Just like dogs, a Great Horned Owl uses its ear tufts to show how it is feeling.

When the owl is irritated the tufts lie flat on its head. When it is curious the tufts stand straight up.

This owl can turn its head further than most creatures because of the extra vertebrae (neck bones) in its neck. Because its eyes are fixed in their sockets, (meaning the eyes cannot look up, down, or side-to-side), the owl must move its whole head to look around.

life cycle In January or February Great Horned Owls begin nesting. The female lays 2 or

3 white eggs. For 30 to 35 days, the male and female take turns sitting on them. When the owlets (baby owls) hatch, the parent owls feed and defend them from predators. If one of the owlets falls out of the nest, the parents will feed it on the ground. The young fledge (grow feathers for flying) in 45 to 55 days. Great Horned Owls often live for more than 12 years.

ecology Great Horned Owls do not make their own nests. They often use an abandoned

hawk or heron nest. Sometimes they nest in tree hollows, abandoned buildings or barns.

The Great Horned Owl eats many different animals, both small and large. The owls will eat squirrels, rabbits, mice, skunks, pocket gophers, voles, snakes, house cats, bats, beetles, frogs, toads, grasshoppers, ducks, grouse, pheasants, and even other owls. The Great Horned Owl has no major predators; it is at the top of the food web.

conservation The Great Horned Owl is very common. Farmers sometimes shoot the owls

because they prey on farm birds like chickens and ducks. To protect the owls from this, the federal government has made it illegal to harm Great Horned Owls.

investigate Owls often swallow small prey whole. Then they regurgitate (throw up) the

bones and feathers or fur in a small lump called an owl pellet. Look for owl pellets under the telephone poles where owls perch. If the pellets are heated to kill germs, they can be dissected (pulled apart) to find the remains of their prey. It is fun to try to put together parts of skeletons to figure out what the owl ate for dinner.

Compare your hearing

Owls have one ear that’s higher than the other. This helps them locate the source of a sound in three dimensions: left or right, near or far, and up or down. How could this ability help a Great Horned Owl?

Have someone in your group move out of your sight and clap from different places, some high and some low. Your head will turn to find the direction of the sound. We humans have trouble finding the height of a sound. Try tipping your head sideways to see if it helps you.

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© Ken Davis

common name Red-tailed Hawk

scientific name Buteo jamaicensis


Chordata Aves Falconiformes Accipitridae

habitat grasslands, forests near open fields, and most areas with short plants

size approximately 0.5 meters

description The Red-tailed Hawk has a dark brown back. In adults, the chest and the

underside of the wings are lighter-colored. They usually have a dark "belly band". Its most obvious feature is a red tail that sometimes has a black stripe at the end. Individual birds vary in color; some are very light, while others are dark brown. Adults look different than young hawks.

fun facts All Red-tailed Hawks have a "chocolate bar" on the underside of each wing. life cycle Female hawks lay 2 to 4 eggs in April or May. They hatch in about 30 days.

The young remain close to the nest until they learn to fly. After they take to the air, they follow their parents on hunting trips and learn to forage (hunt) for themselves. Red-tailed Hawks typically select mates and begin breeding when they are three years old.

ecology Red-tailed Hawks eat rabbits, ground squirrels, snakes, lizards, small birds and

insects. Adult hawks are sometimes eaten by Golden Eagles. Many bird and mammal predators will attack the eggs and young of a Red-tailed Hawk if it leaves them unattended.

conservation These hawks can be found in western Canada, all across the United States, and in Mexico and Central America. They are one of the most commonly seen hawks.

investigate Practice looking up into the sky to spot hawks. Look for the red tail and the

"chocolate bar" on the wing.

Some Red-tailed Hawks migrate while others do not. Why might some stay and some go? How would you study this?

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© Ken Davis

common name Killdeer

scientific name Charadrius vociferous


Chordata Aves Charadriiformes Charadriidae

habitat grasslands, coastal habitats, ponds, rivers, farmlands, gravel roads and rooftops

size 25 cm tall description The Killdeer has a short neck and a chubby, brown body, with a white

underside and a brown face. Two black bands cross the neck and chest. fun facts One of the most interesting things to see is the broken-wing display of a parent

Killdeer. If you approach a Killdeer nest, the parent will move quickly away from the nest and flutter about on the ground, crying and pretending to have a broken wing. When you follow the limping Killdeer, it will remain several steps ahead of you, always moving further and further away from the nest. By pretending to be an easy meal, the parent lures the predator (you) away from the eggs.

life cycle In March, Killdeer select mates and build a small nest on the ground, often out

in the open. The female then lays 4 cream-colored eggs, speckled with black and brown. For 24 to 28 days, the male and female take turns sitting on the nest. A few hours after hatching, the baby birds follow their parents to feeding areas.

ecology The Killdeer eats many insects, including beetles, grasshoppers, flies, and

Mosquitoes. It also preys on aquatic invertebrates, worms and some seeds. Its main predators are larger birds like hawks. Ground predators like raccoons, foxes and coyotes may eat the eggs and young of Killdeer.

conservation Killdeer can live in many different habitats, not all of them natural. They

manage to live in cities. They sometimes make their nests on gravel rooftops and around parking lots. Because they are can live around humans, their population is not as threatened by development as species that require undisturbed habitats.

investigate Killdeer are named for their call, "killdee, killdee, killdee", or "dee, dee, dee". If one calls and attracts your attention, you may be getting too close to its nest. Killdeer often build their nests in the open, rather than in the tall grass. They like to build them near vernal pools, where the plants are very short. What advantage might this provide for the Killdeer?

Even though it sits out in the open, the nest can be very hard to see because its colors blend in with the surrounding plants. What does this disguise do for the Killdeer?

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© George Jameson

common name Western Meadowlark

scientific name Sturnella neglecta


Chordata Aves Passeriformes Emberizidae

habitat grasslands, open fields, meadows, prairies, and plains


description The Western Meadowlark is brown with a short brown and white tail. The sides

and the lower part of the breast are whitish with flecks of black. A black "v" crosses the bright yellow breast.

fun facts The feathers on the breast of the Western Meadowlark are bright yellow with

buff (light tan) tips. In autumn when the feathers are new, we see the feather tips, so the bird’s breast looks buff. By the time spring comes, the feathers are older and the buff-colored tips have worn away. So, in springtime the Western Meadowlark has a bright yellow breast.

life cycle Western Meadowlarks build nests in grasslands and fields on the ground,

nestled in a clump of grass or other plants. They weave dry grass into a bowl shape and line it with hair. The female lays three to five eggs, then sits on them for about two weeks. The young leave the nest before they can fly and must hide in the grass for safety. They gather in groups and look for food. After 6 weeks the young are full grown.

ecology Western Meadowlarks eat grasshoppers, beetles, crickets, spiders, and

caterpillars. Coyotes eat Western Meadowlarks and so do many other birds, including the White-tailed Kites, Swainson’s Hawks, Red-tailed Hawks, Northern Harriers and falcons.

conservation The Swainson’s Hawk is an endangered species and its numbers are decreasing

in the Sacramento Valley. The Western Meadowlark is a much more common

bird. If we preserve good habitat for the meadowlark, in what way can this help protect the Swainson’s Hawk? If we wanted to increase the number of Western Meadowlarks, when would we avoid mowing a grassland?

investigate In the grasslands, watch for the flash of yellow of the Western Meadowlark’s

breast. You are more likely to hear the Western Meadowlark before you see it. Listen carefully for its many beautiful songs, similar to one another. Try imitating them by whistling.

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© David Rosen

common name Red-winged Blackbird

scientific name Agelaius phoeniceus


Chordata Aves Passeriformes Emberizidae

habitat wetlands, cropland, grasslands and roadside ditches

size 18 to 24 cm

description The male Red-winged Blackbird is very handsome, with a solid black body and

bright red patches on his wings. The female is streaky brown. She is seldom seen during nesting because she stays hidden.

fun facts In winter, Red-winged Blackbirds join noisy foraging (hunting and feeding)

flocks of 500 to over 5000 birds of several species: Brewer’s Blackbirds, Tricolor Blackbirds, Yellow-headed Blackbirds, European Starlings and Brown-headed Cowbirds.

The blackbird uses a method called "gaping" to find insects and seeds under the ground. It sticks its closed bill into the ground and then opens it. This makes a hole in the soil, exposing insects and seeds underground.

life cycle In the spring, males arrive at the nesting grounds. These nesting grounds are

often in marshes or in fields near water. The males select an area for their nest. It is usually found in tall wetland plants such as cattails and tules. They sing loudly to claim their territory and to attract a female. In about a week, the females arrive and select the males that have claimed the best territory for nesting and feeding. The males defend their territory and aggressively drive away hawks and other intruders.

It takes 3 to 6 days for the male and female to build a nest of grass and reeds. The female lays 3 or 4 bluish eggs with dark spots. The eggs hatch after 10 to

12 days. The young can fly at 11 to 14 days old but they can swim at 5 to 6 days old. This is important because the nest is often near water.

ecology The Red-winged Blackbird lives in or near wetlands full of cattails and tules.

They also live near water in shrubby thickets of willow or blackberry. In vernal pool grasslands you can find them near the deeper pools where Spikerush grows.

Red-winged Blackbirds forage (hunt) for food in open grasslands, wet meadowsand agricultural cropland. In fall and winter they eat mostly seeds and the grain left in farmer's fields, such as rice, oats and corn. During spring and summer thebirds need more protein to lay eggs and raise their young. To get the extra protein, they add spiders and bugs to their diet including flies, Mosquitoes and ground dwelling insects.

Adult Red-winged Blackbirds are eaten by the Gopher Snake and other snakes. They are also eaten by the Red-tailed Hawk and other hawks. Predators of their eggs and young include snakes such as the California King Snake, raccoons, skunks, and other small mammals.

conservation About 400 million Red-winged Blackbirds live in North America. Although

this bird is common, its populations still suffer from habitat loss. As wetlands and upland foraging habitat disappear, there is less food and shelter for the Red-winged Blackbird. Less habitat means fewer birds.

investigate When you visit wetlands or vernal pool grasslands, listen for the rusty squeak

of the male Red-winged Blackbird. Watch his behavior. Where does he perch tosing? Does he look like he is trying to be noticed? Name one benefit of being noticed. What might be a disadvantage of being so obvious?

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