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. consider each of the following:
   
   a.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?
   
   b. 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 are some examples of foraging behaviour you would need to track if your goal was to calculate the net caloric gain for the foraging hummer?
   
   c.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

a)Hummingbird have the ability to rapidly use their ingested sugar to fuel during their hovering flight powering upto 100% of their metabolic needs with sugars they drink within 30-45 minutes of consumption.These data suggest that hummingbird are able to oxidise sugar in flight muscles at a high rate enough to satisfy their extreme metabolic demand.

b) Foraging behavior of hummingbird are thought to be by repeating order in which they visit following the route called a "trapline". Although there is no quantitative data describing this behavior.The calories loss by hummingbird during their Foraging is 3- 7.6 calorie a day.

c) Hummingbird may pause before inserting their beaks into the flower due to some forces and capillary actions to specify their tongues for drinking the nectars.