Dks

A red dot is more important than a realistic profile.

Head color and shape have little effect on the ability of a red dot to stimulate the begging response.

A red dot elicits a response, even without a head.

Even without a red dot, a long, thin bill elicits the strongest pecking response.

Conclusion: A red dot and/or a long, thin bill release begging responses. Head shape and color have little or no influence.

52.3 Releasing the Begging Response A series of experiments rated the begging responses of herring gull chicks to artificial models of gull heads and bills to discover which features of the parent— head shape, bill shape, or red dot—were releasers of this behavior.

shape of the bill was important, however; a model with a long, thin bill elicited stronger responses than a realistic model. Clearly the chicks had inherited the ability to recognize a simple set of stimuli and respond to them with their also inherited begging behavior. To the ethologists, this finding represented an example of a behavior that was genetically determined rather than learned.

Learning also shapes behavior

Lorenz, Tinbergen, and Karl von Frisch (whose work on honeybees you will encounter later in this chapter) shared a Nobel prize in Physiology and Medicine in 1973 for their contributions to our understanding of animal behavior. New generations of behavioral biologists, however, have moved beyond the ethologists' focus on inherited behavior to show that most behavior involves an interaction between inheritance and learning.

The begging behavior of gull chicks is an example of such an interaction. Although newly hatched chicks respond maximally to simplistic artificial releasers, they gradually learn to discriminate between models and real gull heads, and they eventually beg only from their own parents. Thus, the inherited ability to recognize a simple releaser is subsequently refined by learning.

The early ethologists did not ignore learning or deny that it took place; in fact, they pioneered the study of learning. Tinbergen performed an early study of spatial learning, by which an animal learns to recognize features in its environment. In a classic experiment, he placed objects such as pine cones near the entrance of a nest dug by a female digger wasp. After the wasp left her nest, he moved the objects a short distance away. Upon returning, the wasp oriented to the moved objects and could not find her nest entrance (Figure 52.4). She had learned to recognize objects in the environment to use as orientation cues.

10. Turn the back of the head

10. Turn the back of the head

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