Observational Learning The individual learns from others. Social learning may occur by watching the...

Observational Learning

• The individual learns from others. Social learning may occur by watching the behaviour of another, but it may also occur by simpler means.

Observational learning in Japanese macaques

The habit of washing sweet potatoes in the sea started with a young Japanese macaque female. It spread rapidly to other members of the troop.

Lecture 7. Foraging and Migration

Optimal Foraging

An optimality model for a hypothetical behaviour. According to optimality theory an optimal alternative evolves that maximizes the difference between the cost and benefit and, thus, maximizes fitness.

Handling of food by American crows

• English walnuts break easily, black walnuts do not

• Walnuts crack more easily on hard surfaces

• Walnuts are increasingly likely to crack with each successive drop

• Crows feed in large flocks

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

Proximate explanation: it makes them taste betterUltimate explanation: adding spices to food inhibits the growth of microorganisms and thus protects us from disease.

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

The migratory route of the arctic tern (Sterna paradisea)

Costs of migration

• Energy expenditure• Risk of exposure to severe weather• Predation• Competition for territories

Advantages of migration

• Greater food supply

• Special conditions for breeding

• Reduction in parasitism

• Reduction in competition

for resources

Migratory routes of green sea turtles (Chelonia mydas)

Navigation

Processes that enable an animal to find its way from one specific place to another

• Piloting• Compass orientation• ‘True’ navigation

Piloting

The ability to find a goal by referring to familiar landmarks

Compass orientation

The ability to head in a geographical direction without the use of landmarks.

Experimental relocation of an animal that is using compass orientation causes it to miss the goal by the amount of its displacement

Compass orientation in the European starling

Navigation in the desert ant (Catahlyphis bicolor)

Navigation by dead reckoning

The animal determines its position by using the direction anddistance of each successive leg of the outward trip.A compass can then be used to steer a course directly toward home.

“True” navigation

• Reference to a goal is established regardless

of its location without the use of landmarks

An animal that finds its way by using true navigation can compensatefor experimental relocation and travel toward the goal. This impliesthat the animal cannot directly sense its goal and that it is not using familiar landmarks to direct its journey.

A famous homing pigeon

Two hundred fifty American soldiers in World War I owed their livesto this homing pigeon, which carried a distress message to its handler.Reinforcements were sent to rescue the beleaguered battalion.

Gustav Kramer’s sun-compass orientation experiment

Birds compensate for the sun’s apparent motionCaged starlings alter the direction of their attemptedmigratory movement with respect to the artificial sun, as if assuming that the ‘sun’ is moving.

Birds use the sun as a navigational cueUsing mirrors, Kramer altered the apparent position of the sun. The birds shifted their migratory direction by the same angle

Stars as visual cues in navigation

The stars rotate around Polaris, the North Star. The center of rotation of the starstells birds which way is north. The positions of stars in the northern sky during the spring are shown here. The closed circles indicate star positions during the early evening, and the open circles indicate the positions of the same stars six hours later.