Question

3. The increase in singing that male birds exhibit in the spring seems to be prompted by an increase in their testosterone levels. (6 marks total)

   1. a) Are testosterone levels a proximate or ultimate cause of singing? Explain. (3 marks)

      Note: do (b) or (c), as appropriate.

   2. b) If they are not a proximate cause, what is? Explain. (3 marks)

   3. c) If they are not an ultimate cause, what is? Explain. (3 marks)

Answer 1

a) Testosterone level is proximate cause of singing. High level of testosterone induces the sexual desire of the male bird. He start to attract female birds for mating.

c) Singing of a male bird is a courtship behaviour. Courtship behaviour are shown to the female birds by the male bird to attract them to mate with him. The good the courtship behaviour, the more the chance to mating. The male bird with good singing voice will attract the female birds frequently.