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

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

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 and distance 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 compensate for experimental relocation and travel toward the goal. This implies that 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 lives to 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 use the sun as a navigational cue Using mirrors, Kramer altered the apparent position of the sun. The birds shifted their migratory direction by the same angle Birds compensate for the sun’s apparent motion Caged starlings alter the direction of their attempted migratory movement with respect to the artificial sun, as if assuming that the ‘sun’ is moving.

Stars as visual cues in navigation The stars rotate around Polaris, the North Star. The center of rotation of the stars tells 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.