Behavioral Ecology

Q1.25. The giving-up density (GUD) of gray squirrels feeding on college campuses tends to be lower than that of squirrels feeding in suburban back yards. Which of the following hypotheses is consistent with this result? Squirrels perceive predation risk to be higher in suburban back yards. Squirrels perceive predation risk to be higher on college campuses. Squirrels are better fed on college campuses, and thus feed less intensively. Squirrels benefit more by foraging in suburban back yards than on college campuses.

Squirrels perceive predation risk to be higher in suburban back yards.

Q1.22. The industrious beaver is a good example of a central-place forager. Given this, which of the following statements is most likely to be true? During the mating season, beaver travel to centralized meadows where they compete for mates. A colonial species, numerous beaver families will each build a lodge on the edge of a central pond. All beaver in an area forage for aquatic plants that grow in a single, centralized location. Beaver venture out from their lodges to collect plant matter, returning to store this food in or near the lodge.

Beaver venture out from their lodges to collect plant matter, returning to store this food in or near the lodge.

Q2.26. Later in the season, stoneflies have disappeared and house martins must choose between caddisflies and mayflies. This means that the critical search time for the preferred (more profitable) prey is 2 seconds. Assuming birds forage optimally, which prey items should a house martin eat? Caddisflies only Mayflies only Both caddisflies and mayflies There is not enough information to answer the question.

Both caddisflies and mayflies

Q3.23. Which of the following statements about game theory is NOT true? Game theory accounts for the expected costs and benefits associated with different behaviors. Game theory accounts for strategies chosen by others when assessing the benefit of a behavior. Game theory assumes players will seek to maximize some important payoff, such as fitness. Game theory assumes that a strategy's payoff is not dependent on strategies adopted by other players.

Game theory assumes that a strategy's payoff is not dependent on strategies adopted by other players.

Q2.23. House martins (depicted on the right) feeding their young in the nest are clear examples of central-place foragers. Imagine that a house martin travels to two different patches to collect meals for its chicks. The patches are identical except that one is farther from the nest. According to the marginal value theorem, which statement best describes how an optimally foraging house martin should behave? It should stay longer in and collect a larger load from the closer patch. It should stay longer in and collect a smaller load from the closer patch. It should stay longer in and collect a larger load from the more distant patch. It should stay longer in and collect a smaller load from the more distant patch.

It should stay longer in and collect a larger load from the distant patch.

Q1.26. The social bacteria M. xanthus coordinate group attacks on other bacteria, rapidly consuming entire colonies of prey. Researchers may be interested in many different aspects of this behavior. Recall Tinbergen's classification of questions about behavior (click here to go back to page 2 and review). Which of the following hypotheses suggests the potential ADAPTIVE VALUE of such a coordinated attack? M. xanthus use chemical signals that are exchanged between neighbors to coordinate their attacks. Coordinated attacks are unique among bacteria, having evolved in only M. xanthus. M. xanthus that engage in coordinated attacks feed more efficiently and reproduce faster than those that don't. M. xanthus only engage in coordinated attacks if they have reached a certain, more mature, developmental stage.

M. xanthus that engage in coordinated attacks feed more efficiently and reproduce faster than those that don't.

Q1.23. Late each summer, migrating rufous hummingbirds stop in Arizona, where they establish and defend territories. Larger territories contain more flowers, provide more energy in the form of nectar, and are harder to defend. Researchers Astrid Kodric-Brown and James Brown developed a cost-benefit model to help explain observed variation in territory size (S). A modified version of their model is shown to the right. Based on this model—and assuming optimal behavior—how large an area should a hummingbird defend (referring to labels on the x-axis)?

S2

Q2.22. Which of the following is NOT an advantage of using optimality models to study behavior? The models make clear, testable predictions about how individuals should trade off the costs and benefits of a behavior. The models always perfectly predict an individual's behavior. The model's assumptions highlight the conditions under which the model's predictions are expected to hold. New avenues of study are suggested when model predictions and empirical observations diverge.

The models always perfectly predict an individual's behavior.

Q3.25. Imagine that a drought occurs and some lakes dry up, resulting in fewer loon territories. The remaining territories, due to their scarcity, are more highly valued. All else being equal, how would this change affect the outcome of the game, and why? Doves would increase in proportion, because the cost of fighting (i.e., injury) would be smaller. Hawks would increase in proportion, because the cost of fighting (i.e., injury) would be smaller. Hawks would increase in proportion, because the benefit of victory would be greater. The proportions of neither Hawks nor Doves would change, because territory availability isn't relevant to costs or benefits.

The proportions of neither Hawks nor Doves would change, because territory availability isn't relevant to costs or benefits.