Question

Q1.23. Late each summer, migrating rufous hummingbirds stop in Arizona, where they establish and defend territories. Larger territories contain more flowers, provide more energy in the form of nectar, and are harder to defend. Researchers Astrid Kodric-Brown and James Brown developed a cost-benefit model to help explain observed variation in territory size (8). A modified version of their model is shown to the right. Based on this model—and assuming optimal behavior-how large an area should a hummingbird defend (referring to labels on the x-axis)? Si Benefits/Costs 01.24. Kodric Brown and Brown wanted to explore how reducing territory quality would affect foraging behavior. They created low-density territories by removing half the flowers, and they compared them to high-density, unmanipulated territories Which of the four graphs below best illustrates how reducing flower density will affect the cost (C) or benefit (B) curve of the low-density territory? (Subscripts indicate whether the curve represents a territory with a high-density (H) or low density (L) of flowers.) S, S, S Territory size S (m) Cost bene model of belly in tous winged in manipulated patches with high denses of flowers Bene Curve, describes how necta harvestrate increases krilorysle Assire increases the number of flowers protected increases, but so does the time needed to viedt each fowe placing an sepert on the territory wide arrest rate Costs associated with defense increase with florystre as indicated by the con curve

Answer 1

1. At the territory size of S2, the benefit is high and the cost is less and at S3 and S1, the cost and benefit are equal and at S4, the cost is too high and benefit is very less. Hence at optimal conditions, the hummingbird should defend a territory size of S2. Hence the correct answer is: S2.

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