On April mornings, you step outside your front door and notice the singing of a male robin. At that time you also observe that the female of the pair is building a nest in a nearby tree. A month later you observe the pair feeding their nestling offspring. Which of the following is a question about the ultimate cause of the behavior of these birds?
A) Did the male bird begin to sing in April because the photoperiod had increased to a critical length?
B) What were the relative roles of genes and experience in causing the female robin to build her nest out of particular building materials and to place it in a particular location?
C) What combination of internal physiological factors and external cues stimulates the parents to feed their nestlings?
D) Do robins that begin nesting in April raise more offspring than they would raise if they delayed nesting until June, and if so, why?
E) None of the above

Question

Quizplus · Accepted Answer

This question asks about the ultimate cause, which is the reason why a behavior evolved. The relative timing of nesting and offspring production in this species is an evolutionary question about why the behavior evolved, and whether it confers any fitness advantages. The other answer choices focus on more proximal causes, such as physiological or genetic mechanisms, or external cues that trigger behavior.

On April Mornings, You Step Outside Your Front Door and Notice