Question

1. Trochilidae (or Hummingbirds) have evolved as specialist nectar eaters. Up to 90% of a Hummingbird’s diet can consist of nectar. Their beaks, which are particularly slender and long, are well adapted for obtaining nectar. For example, the buff-tailed sicklebill (Eutoxeres condamini) has a curved beak, which supports its feeding on tube-like flowers, like Heliconias. Even their tongue is long – twice as long as the bill – so that they can reach even further down the tube! Researchers of this hummingbird have observed that individual birds practice ‘circuits’, or patterns, from one flower to the next as they feed. Over a 30 minute period, an individual bird could make one entire circuit, ending back at the flower it started with. Given what you have learned in this course, consider each of the following: (total 6 marks, 2 marks each)

   1. If a researcher observed this behaviour and assumed that the bird was showing optimal behaviour by obtaining more energy than it is using, s/he may be wrong. Why?

   2. If you were a researcher who wanted to collect data in order to measure whether or not the hummingbird was behaving optimally while foraging, what types of data would you collect to determine if the bird was foraging optimally?

   3. Researchers have also observed that hummingbirds may pause before they actually insert their beaks into the flowers. Could this behaviour be consistent with a hypothesis that suggests the bird is foraging optimally? Why or why not?

Answer 1