Animal Behavior

If an egg rolls out of the nest, a mother greylag goose will retrieve it by nudging it with her beak and head. If researchers remove the egg or substitute a ball during this process, the goose continues to bob her beak and head while she moves back to the nest. Explain how and why this behavior occurs.

Suppose you exposed various fish species from the minnows’ environment to the alarm substance from minnows. Thinking about natural selection, suggest why some species might respond like minnows, some might increase their activity, and some might show no change.

How is the lunar-linked rhythm of fiddler crab courtship similar in mechanism and function to the seasonal timing of plant flowering? (See Concept 39.3.)

How might associative learning explain why different species of distasteful or stinging insects have similar colors?

How might a learned behavior contribute to speciation? (See Concept 24.1.)

How might you position and manipulate a few objects in a lab to test whether an animal can use a cognitive map to remember the location of a food source?

How does the average number of drops required to break open a whelk depend on platform height for a drop of 5 meters or less? For drops of more than 5 meters?

Total flight height can be considered to be a measure of the total energy required to break open a whelk. Why is this value lower for a platform set at 5 meters than one at 2 or 15 meters?

Compare the drop height preferred by crows with the graph of total flight height for the platform drops. Are the data consistent with the hypothesis of optimal foraging? Explain.

In testing the optimal foraging model, it was assumed that changing the height of the drop only changed the total energy required. Do you think this is a realistic limitation, or might other factors than total energy be affected by height?

Researchers observed that the crows only gather and drop the largest whelks. What are some reasons crows might favor larger whelks?

It turned out that the probability of a whelk breaking was the same for a whelk dropped for the first time as for an unbroken whelk dropped several times previously. If the probability of breaking instead increased, what change might you predict in the crow’s behavior?

Why does the mode of fertilization correlate with the presence or absence of male parental care?

Balancing selection can maintain variation at a locus (see Concept 23.4). Based on the foraging experiments described in this chapter, devise a simple hypothesis to explain the presence of both for R and s alleles in natural fly populations.

Suppose an infection in a common side-blotched lizard population killed many more males than females. What would be the immediate effect on male competition for reproductive success?

Explain why geographic variation in garter snake prey choice might indicate that the behavior evolved by natural selection.

Suppose an individual organism aids the survival and reproductive success of the offspring of its sibling. How might this behavior result in indirect selection for certain genes carried by that individual?

Suppose you applied Hamilton’s logic to a situation in which one individual is past reproductive age. Could there still be selection for an altruistic act?

Which of the following is true of innate behaviors? 

(A) Their expression is only weakly influenced by genes. 

(B) They occur with or without environmental stimuli. 

(C) They are expressed in most individuals in a population. 

(D) They occur in invertebrates and some vertebrates but not mammals. 

According to Hamilton’s rule, 

(A) natural selection does not favor altruistic behavior that causes the death of the altruist. 

(B) natural selection favors altruistic acts when the resulting benefit to the recipient, corrected for relatedness, exceeds the cost to the altruist. 

(C) natural selection is more likely to favor altruistic behavior that benefits an offspring than altruistic behavior that benefits a sibling. 

(D) the effects of kin selection are larger than the effects of direct natural selection on individuals.

Female spotted sandpipers aggressively court males and, after mating, leave the clutch of young for the male to incubate. This sequence may be repeated several times with different males until no available males remain, forcing the female to incubate her last clutch. Which of the following terms best describes this behavior? 

(A) polygyny 

(B) polyandry 

(C) promiscuity 

(D) certainty of paternity

A region of the canary forebrain shrinks during the nonbreeding season and enlarges when breeding season begins. This change is probably associated with the annual 

(A) addition of new syllables to a canary’s song repertoire. 

(B) crystallization of subsong into adult songs. 

(C) sensitive period in which canary parents imprint on new offspring. 

(D) elimination of the memorized template for songs sung the previous year.

Although many chimpanzees live in environments with oil palm nuts, members of only a few populations use stones to crack open the nuts. The likely explanation is that 

(A) the behavioral difference is caused by genetic differences between populations. 

(B) members of different populations have different nutritional requirements. 

(C) the cultural tradition of using stones to crack nuts has arisen in only some populations. 

(D) members of different populations differ in learning ability. 

Which of the following is not required for a behavioral trait to evolve by natural selection? 

(A) In each individual, the form of the behavior is determined entirely by genes. 

(B) The behavior varies among individuals. 

(C) An individual’s reproductive success depends in part on how the behavior is performed. 

(D) Some component of the behavior is genetically inherited.

You are considering two optimal foraging models for the behavior of a mussel-feeding shorebird, the oystercatcher. In model A, the energetic reward increases solely with mussel size. In model B, you take into consideration that larger mussels are more difficult to open. Draw a graph of reward (energy benefit on a scale of 0–10) versus mussel length (scale of 0–70 mm) for each model. Assume that mussels under 10 mm provide no benefit and are ignored by the birds. Also assume that mussels start becoming difficult to open when they reach 40 mm in length and impossible to open when 70 mm long. Considering the graphs you have drawn, indicate what observations and measurements you would want to make in this shorebird’s habitat to help determine which model is more accurate.

We often explain our behavior in terms of subjective feelings, motives, or reasons, but evolutionary explanations are based on reproductive fitness. Discuss the relationship between the two kinds of explanation. For instance, is an explanation for behavior such as “falling in love” incompatible with an evolutionary explanation?

Scientists studying scrub jays found that “helpers” often assist mated pairs of birds by gathering food for their offspring. 

(A) Propose a hypothesis to explain what advantage there might be for the helpers to engage in this behavior instead of seeking their own territories and mates. 

(B) Explain how you would test your hypothesis. If it is correct, what results would you expect your tests to yield.

Researchers are very interested in studying identical twins separated at birth and raised apart. So far, the data reveal that such twins frequently have similar personalities, mannerisms, habits, and interests. What general question do you think researchers hope to answer by studying such twins? Why do identical twins make good subjects for this research? What are the potential pitfalls of this research? What abuses might occur if the studies are not evaluated critically? Explain your thinking.

Learning is defined as a change in behavior as a result of experience. In a short essay (100–150 words), describe how heritable information contributes to the acquisition of learning, using some examples from imprinting and associative learning.

Acorn woodpeckers (Melanerpes formicivorus) stash acorns in storage holes they drill in trees. When these woodpeckers breed, the offspring from previous years often help with parental duties. Activities of these nonbreeding helpers include incubating eggs and defending stashed acorns. Propose some questions about the proximate and ultimate causation of these behaviors that a behavioral biologist could ask.