Functional ResponseLab 10

Turn in proposals on front table.

Today’s Objectives

• Understand functional response of a predator at varying prey densities

• Understand what contributes to the three different types of functional response curves

Optimal Foraging Theory

• Foraging is a trade-off between energy costs and gains

• Accounting for:– Search time– Handling time– Energy gained

Optimal Prey Size

Handling time

Very high medium low

Energy Gained

high medium Very low

Predator/Prey Interactions

Changes in # of predators

in response to # of prey

Changes in predator’s rate of consumption based on prey density

Functional Response Curves• A single predator’s consumption rate of prey

In relation to the prey population

• There are 3 general classes

of functional response ( I, II, III)

Type I

Linear increase in consumption

Little to no handling time

Type II

Typical of predators that specialize on one or a few prey

species

06_23.jpg

Type III

• Prey refugia• Low density

• Learning–Search image–Where to find prey

• Prey Switching

Prey density effects on predator consumption rate >> Part 1: No handling time <<

You will be the predators.

Black-eyed peas are the prey.

See directions in handout/coursepack.

Prey density effects on predator consumption rate

>> Part 2: Handling time <<

- You are the predators

- Rocks are the prey- Handling time is affected by your

capturing tools (chopsticks)

1) Make predictions (on handout)

2) Capture prey at each density. Time limit=30 sec

3) Record handling time by stopping timer when all prey have been captured (up to 30 sec)

Prey density effects on predator consumption rate

>> Part 3: Refugia <<

You are the predators

Glass beads are the prey

Handling time is affected by your capturing tools (spoons)

1) Make predictions (on handout)

2) Capture prey at each density (move around room to each density). Time limit=30 sec

Announcements

• Read Lab 2: Estimating Populations

• pgs. 9-16

(different from what’s on syllabus)