Lecture 19 (higher level)

MVT = marginal value theorem

What is the difference between a functional response and a numerical response?

Functional = per-capita consumption

Numerical = predator population growth as prey density changes. [Slide 5]

Why is the Type II functional response more realistic than Type I?

Because it incorporates handling time, which limits consumption rates. [Slide 5]

What mechanism causes the sigmoidal shape of the Type III response?

Low-density refugia and poor predator search efficiency at low prey density. [Slide 5]

Why do generalist predators switch diets as prey abundance shifts?

They maximize profitability by taking more abundant prey when available. [Slides 3–4]

How does nocturnal hunting influence predator morphology?

It selects for large eyes that enhance low-light visual sensitivity. [Slide 3]

Why is net energy gained per unit time the basis of optimal foraging models?

It directly predicts fitness outcomes via energetic efficiency. [Slide 6]

What does handling time represent?

The time required to capture, consume, and digest prey. [Slide 5]

Why may predators stay longer in low-quality patches than expected?

Travel times make longer stays optimal even in poor patches (MVT). [Slide 10]

What role does risk of predation play in patch choice?

It lowers patch profitability, prompting earlier departure. [Slide 9]

Why can specialization be risky for predators?

Declines in preferred prey greatly reduce energy intake. [Slide 4]

How does search-image formation influence functional responses?

It improves detection of abundant prey, contributing to Type III patterns. [Slide 5]

Why do crows drop nuts on pavement more than soil?

Pavement provides higher cracking success. [Slide 9]

What determines the optimal moment a forager should leave a patch in MVT?

When the instantaneous intake rate falls below the tangent line determined by travel time. [Slide 10]

How does prey defensive evolution affect functional responses?

Increased handling time shifts predators toward other prey types. [Slides 5–7]

Why is optimal foraging theory framed as increasing benefits and lowering costs?

Because natural selection favors behaviors that maximize net energy intake. [Slides 6–7]