Behavioral Ecology

views updated

Behavioral Ecology

Behavior is what animals do and why they do it. Behavioral ecology examines the evolution of behaviors that allow animals to adapt to and thrive in their habitats.

There are two broad categories of behavior—learned and instinctive. Instinctive behavior is a pattern passed genetically from one generation to the next. A spider, for example, never needs to see another spider weave a web to know exactly how, where, and when to do it. This information is carried innately with the spider and allows it to carry out many of its life processes without ever having to think about them. The disadvantage to instinct is that is inflexible and does not allow the animal to change when the behavior is no longer appropriate. The armadillo's instinctive upward leap when threatened worked fine until the animal encountered a new environmental hazard—the automobile. Learned behavior , in contrast, is the result of experience accumulated and assimilated throughout a lifetime that allows the animal to adapt to unpredictable changes.

A behavioral ecologist studies patterns of behavior that fall somewhere between instinctive and learned. They include:

Reflex: A rapid automatic response to a stimulus. Hedgehogs automatically curl into a ball when threatened.
Conditioned reflex: An instinctive reflex that can be trained to occur under different conditions. A racehorse will go faster when flicked with a whip because it associates the whip with its traditional predator, a large cat, clawing at its back.
Migration: A seasonal movement to a more favorable summer or winter environment. One of the most phenomenal migrations is that of the monarch butterfly, which spans thousands of miles and two generations. The young are genetically programmed to return to the fields their parents left.
Hibernation and estivation: A state of torpor, or lowered metabolic rate resembling sleep, entered into by some animals in order to survive severely cold winters or hot, dry summers.
Imprinting: Memorization by a young animal of the shape, sound, or smell of their parents or birthplace during a very brief period following birth. If the parent is absent, the baby will imprint on the first object it senses, giving rise to the sight of ducklings that think humans are their parents or kittens that have imprinted on dogs.
Courtship: The special signals and complicated rituals that allow male-female bonds to occur for mating purposes. These behaviors assure the intentions and, consequently, the safety of both partners, who might attack or devour an approaching mate if the signals are unclear.
Mimicry: The evolution of a harmless animal to look or behave like a dangerous animal. The viceroy butterfly mimics the coloration of the poisonous monarch, which most birds are genetically programmed to avoid.
Preadaptation: A mixture of instinctive and learned behavior. Purple martins who once nested on cliffs have learned to use human-built structures to extend their ranges.

Behavioral ecologists who study animals closely in natural settings report numerous incidents of watching them encounter a new situation and think out a new response. Harvard biologist E. O. Wilson describes watching several beavers whose dam had been vandalized come up with a solution to the problem. Because the water flow was too strong to be stopped by their instinctive techniques, the beavers came up with a new and successful idea of patching the dam with gooey underwater mud and debris. Wilson is convinced that this showed the beavers' ability to evaluate a problem and solve it with reasoning.

For many years it has been taboo for scientists to propose the idea that animals consciously reason. As biologist Jane Goodall explained, "If you admit that animals have sentience and emotion, you have to take a long, hard look at how we abuse them."

see also Acoustic Signals; Behavior; Communication; Courtship; Social Animals; Sociobiology.

Nancy Weaver