Classify each of the following descriptions as either a proximate or an ultimate cause of behavior. For all proximate causes, speculate about a possible ultimate cause of the behavior.

a. A surge of epinephrine initiates a flight response in a gazelle.

b. Turtles use Earth’s magnetic field lines as guides during migration.

c. A small mammal ignores low-energy food sources that are difficult to obtain, maximizing energy gain from foraging.

d. A bird distracts a predator near its nest, increasing the nestlings’ chance of survival.