Birds – Part IV

VERTEBRATE ZOOLOGY (VZ Lecture26 – Spring 2012 Althoff - reference PJH Chapters 16-17)

Bill Horn

Wing Proportions• Over time (i.e., evolutionary time), major changes

have taken place in the surface area present in bird wings: a) some large wings in proportion to body

light wing loading vs. b)

some small wings in proportion to bodyheavy wing loading

• Also, wings may be long and pointed, short, or rounded

• Also, wings can have high camber or be relatively flat

• Also, width & degree of slotting can vary

Powered flier vs. Soaring form

• Type of flier reveals ____________ in length of various __________ of the wing:1) hand 2) forearm 3) upper arm

• Hummingbirds: very fast, powerful wing beats*longer hand bones > forearm + arm*mostly primaries, only 6-7 secondaries

• ______ bird (marine species): powered flight ANDsoaring (lowest wing loading of any bird)

• Albatross: extremely long wing, especially in upper arm: up to 32 secondaries

Fig. 17-11 p449, PJH RELATIVE LENGTHS

Upper

armforearm hand

Humm

ingbir

d

Frigat

e bir

d

Albatro

ss

4 Basic Structural & Functional Wing Types

• __________________ – typical of seabirds like the albatrosses and shearwaters. Requires strong and persistent winds. Wings…

A) long, narrow & relatively flat B) lack slots in outer primaries.

-bird glides downward with increasing speed, and gains altitude when gliding into the wind

-Also needs to be “vertical” wind gradient

1

4 Basic Structural & Functional Wing Types

• __________ – typical of forest and woodland birds (pheasant, quail, ruffed grouse) where they must maneuver around obstructions. Low aspect ratio. Wings…

A) tend to be highly camberedB) usually have a high degree of slotting in

the outer primaries

-typically, these species have rapid flapping but relatively slow flight. -Overall, good agility in “tight” places.

2

4 Basic Structural & Functional Wing Types

• ___________________– typical of aerial foragers, those that make long migrations, or have a heavy wing loading that enables another aspect of their lives (like diving). Wings….

A) have flat profile (i.e., little camber)B) often lack slots in outer primaries

-typically, associate with fast-flying birds, with wings usually in “swept-back” position

3

4 Basic Structural & Functional Wing Types

• ___________ – typical of birds that exhibit “static” soaring type of flight. Vultures, eagles, many hawk species (broad-wings especially) storks, and other large birds. Wing has intermediate aspect ratio between the elliptical and the high aspect ratio wing design. Wings… A) have deep camber B) marked slotting on the primaries

-these are birds known to “ride” the thermals-deep slotting permits slow flight yet high lift-individual feathers adjust to changes in

currents rather than entire wing moved

4

Fig. 17-12 p449, PJH

DYNAMIC SOARING(shearwater)

HIGH ASPECT RATIO(swallow)

HIGH LIFT(rough-legged hawk)

ELLIPTICAL(pheasant)

1

2

3

4

Hind Limbs• Generally, the majority of bird species have two

modes of locomotiona) bipedal walking or swimming with the hind

limbsb) flying with the forelimbs

• Terrestrial use of hind limbs: --walking, hopping, and perching

• Modifications associated with quadrapeds are generally also associated with terrestrial bird designs

1) progressive ________ in length of distal portion relative to proximal toe

2) _________ in area of the foot surface touching ground

3) _________ in the number of toes

Hind Limbs• No 5-toed birds• Generally, reduction in length and number of toes

(especially the amount of surface area in contact with the ground) _____ what is present among most mammal species…but there is some. Example ostrich has 2 toes. And, many bird species have only 3 forward toes.

2

3

3

12 2

“Hoppers”

• Moving forward, feet together• Only found in perching and/or arboreal birds….

• Highly developed in passerines (think golden-winged warbler, Kirtland’s warbler, grasshopper sparrow,)

a) some cannot walk—legs & feet cannot move independent of each other.

b) some can walk & hop

“Perching”• Does not require much

energy• Tendons that flex the toe

can lock the foot a tight grip—on rear side of ankle

• No muscular contraction is required to hold the toes closed

• Hobnail-like projections on tendons lying underneath the toe bones mesh with ridges on the inside sruface of the surrounding tendon sheath

Toe arrangements

_______________

1

2 3 4

Pamprodactyl

Syndactyl2 & 3 fused

Zygodactyl

Heterodactyl

Fig. 17-16 p454, PJH

some ___________ BIRDS

Webbed and Lobed Feet

LobedPower-strokeforward stroke (front) & side

views

Partial webbing(3-toes)

ducks

Totipalmate

(4-toes)

cormorants

Feeding & Digestion

• Many specializations—especially with respect to beak & tongue designs

• Beak designs include:insect catchers insect netfruit plucker generalized billflesh tearer dip netfish grasper fish spearmud sifter water strainerseed cracker pine seed extractor

Fig. 17-18 p456, PJH

Fig. 17-19 p457, PJH

• Skull ___________ possible in most birds

• Influences feeding capabilities

• Combination of inward and outward flexion results in _______ expanded in horizontal and vertical direction

Inward flexion

Inward flexion

outward flexion

outward flexion

Fig. 17-19 p457, PJH

American woodcock

• For probing species, ability to raise the tip of the bill without opening the mouth provides opportunity to exploit food sources in the sand (some shorebirds) and/or soil (woodcock)

• Woodcock shown here has beak that is 3+ inches long—probes for earthworms

Fig. 17-20 p458, PJH

Woodpecker—probing tongue

Anteater---probing

tongue with different

origin for tongue

attachment (on sternum)

but same result

NECTAR FEEDERS

magnificent hummingbird

green violet-ear hummingbird

fiery-throated hummingbird

volcano hummingbird

• Note the __________ of the bill

• Note the __________ of the bill

food-straining (NORTHERN SHOVELER DUCK)

Fringed, tubular nectar feeder fruit-eater (Diard’s trogon)

fish-eater (sooty shearwater)

(bananaquit)

general feeder (robin) probing-spearing (woodpecker)

food-straining (NORTHERN SHOVELER DUCK)

fringed, tubular nectar feeder

fruit-eater (Diard’s trogon)

fish-eater (sooty shearwater)

(bananaquit)

Digestive System

• Oral cavity• Pharynx• Esophagus• Crop (*)• Proventriculus• Gizzard• Pylorus• Small intestine• Large intestine• Cloaca

• Liver

• Pancreas

MAIN TRACT AUXILLARY

Earthworm

mouthpharynx

esophagus

small intestine

anus

Fig. 17-22 p460, PJH

esophagus

crop

proventriculus

gizzardpylorus

small crop

Small

Gizzard

Largeand

muscular

Fig. 17-23 p461, PJH

Starling (Sternus vulgaris)

_____________ in diet

length of intestine

Changes in Starling GI tract

• Response to ______________ availability of certain food types

• Higher plant content in diet (need more time to digest to extract nutrients) results in longer intestinal tract (~ _____ increase in length)

• Besides anatomical changes, digestive enzyme composition changes, too, to different food types they consume:

a) simple sugars in fruit vs.

b) fat and protein in animal-based food

Fig. 17-25 p464, PJH

Eye Anatomy

Vitreous humor

• Birds have large eyes…so large that the brain is displaced dorsally and caudally

• In some species the eyes meet in the midline of the skull

• _______ structure here: the ______

the PECTEN• Shape varies from species-to-

species

• Consist of blood capillaries surrounded by pigmented tissues and covered by a membrane but lacks muscles and nerves

• Function: __________________a) reduction of glare?b) mirror to reflection objects above?c) visual reference point ?

• May provide nutrition to retinal cells…& remove metabolic waste from vitreous humor

Fig. 17-25 p464, PJH

Eye Shapes

• The two to the right, especially the far right, won’t fit completely into the skull unless they were more of this tubular design (vs. flatten)

_____________

FLATTEN

most falcons

GLOBULAR

owls & some eagles

TUBULAR

• Rods and cones found in ____________ • Rods do _____ require much light to stimulate them

vs. cones that require a considerable amount of light.

• General trend, nocturnal species have considerably more rods than cones. Opposite trend for diurnal species (goes for mammals, too)

• Humans: ~________ cones per mm2

• House sparrow: ~________ cones per mm2

• Common buzzard: ~________ cones per mm2

• RESULT extremely _____________ color vision!• Also, some birds can see near-ultraviolet

wavelengths

Cones vs. Rods

Fig. 17-26 p465, PJH

Hearing-related: skull asymmetry

• Hearing sensitivity in birds appears to match, on average, that of humans despite smaller amount of structure/size of ears

• This “equalling out” is achieved by a large tympanic membrane (TM) …and owls are “the” kings when it comes to the TM size relative to the skull.

• Owls also have large cochlae and auditory center

Sense of Smell• In most species, very poorly developed• Olfactory capability reflected in the size of the

olfactory bulbs and associated processing area in the brain

• Noted exception: kiwi from New Zealand. A terrestrial bird has nostrils at the end of its long bill and uses that sense to locate earthworms underground

• Turkey vultures follow airborne odors of carrion to the vicinity of a carcass…most of these scavenging species have featherless heads that reduce the risk not being able to ‘dry’ off the head or serve host to parasites

Sense of Taste• Birds have few taste buds!

Humans ~10,000chicken ~ 24 (rear of tongue &

pharynx) pigeon ~ 37 “J. quail ~ 62 “

• Birds like chili peppers. Active ingredient in chili peppers are ___________. Have a “flaming” effect on the mammalian oral epithelia and taste buds. Normal concentrations repel rodents but birds do not find chili peppers distasteful. Birds actually attracted to them because of high vitamin, protein and lipid content.

…any benefits to the pepper plant species?