Question

12. Researchers are attempting to understand whether the floral nectar consumption by a particular hummingbird species conforms to the expectations of optimal foraging theory. Describe two experiments that could be performed to assess this.

One will be an observational experiment, where foraging is observed in the wild, throughout the year, without manipulation. Assume that cold temperature is the key environmental constraint that limits the birds’ abilities to be choosy (i.e. hint, look at the salmon experiment from our lecture). Also assume these birds choose among 3 different types of flowers/nectar that are available throughout their active season: A, B, and C. A has the highest amino acid content and C has the lowest. All have equal amounts of energy. A is the hardest to find, followed by B, and then C.

The other will be a manipulative experiment in which the search time is varied. In this one you create an arena with 2 types of artificial flower, each with different qualities of nectar (i.e. different amino acid content). The flowers differ in colors that the birds can distinguish, but are otherwise identical (i.e. the handling time is kept the same). You have to set things up so that the cost-to-benefit ratio of looking for the higher nutrition flower is changed across 2 treatments. Hint: think along the lines of the conveyor belt experiment.

Be sure to explicitly state your dependent and independent variables and to describe the results expected if the birds do indeed conform to the expectations of optimal foraging theory

Answer 1

Optimal foraging theory predicts that organisms will maximize their foraging efficiency by balancing time spend feeding and time spent searching for new feeding sites. It is very important in hummingbirds we need a constant energy requirement and high metabolism.

Introduction

1. According to the marginal value theorem, animals for age in a patch until their rate of energy gain is less than or equal to the potential energy gain from the habitat.

2. Hummingbirds need large intake of energy due to high metabolism and high energy loss for their size.

3. Hummingbirds prefer nectar because it provides as a quick source of energy.

4. They are the best organisms to study optimal for aging theory because if they do not choose a for raising strategy that maximize their energy intake, they will perish.

5. Hummingbirds foraging cues depends on visual factors.example, colour of the flower, size of the flower etc.

Results expected

Experiment 1

In this experiment foraging is observed in the wild without manipulation. Here, cold temperature is the key constraint that limits the birth ability to be choosy. This is because the food may freeze making it unable for the bird to consume it. In the given scenario bird if choosing between flowers A ,B ,C in which A >B>C in amino acid content and all have equal amount of energy. A> B >C is hardest to find .In this case ,bird will prefer flowers in the order C> B>A .

Resons

1. Hummingbirds prefer nectar solutions with less amino acid content. They have taste receptors which even can understand 1 percentage change in the sucrose solution. So they will prefer C flowers or B flowers. C flowers are preferred because they are easily available. B flowers are preferred for balanced nutrition.

2. C flowers are easily available so according to the marginal value theorem and optimal foraging theory they will prefer them more.

Experiment 2

In this experiment we create and manipulated Arena of artificial flowers in different quality of Nectar marked in different colours here ,the result will be according :

1. The departure rule : hypothesis indicates that Hummingbird should remain in a flower when its estimate of Nectar yield at next flower is equal to the average time per flower multiplied by overall growth rate of Nectar intake in the whole flower patch. That is , if it should leave , if expected nector yield is less than this 'expectation threshold'.

2. The calculate the nectar yield by:

* correlations between lecture volumes of both kind of flowers.

* patterns of revisitation of flowers

3. The likely subject flowers on the following information:

* nectar volume of flowers.

*Number of flowers available.

*Balanced nutrition.