8. Capture recapture technique

What can’t quadrats be used for

Assessing populations of moving animals

Why can’t quadrats be used for moving animals

Could count same animal more than once

First step of capture recapture

Number of individuals of particular species captured

Second step of capture recapture

Animals marked so they can be identified + released into habitat

Third step of capture recapture

Another sample captured, Marked individuals in second sample are same as original sample

Why does enough time have to have passed

The marked ones need to mix with rest of population

What can’t there be when capture recapturing

Immigration or emigration

What must capture recapture must not do

Affect survival chances of animal e.g. making it easier for predator to see them

What must the marking also not do

Affect chances of recapture

What determines the size of an animal population?

The capture recapture technique

What does the capture recapture technique do?

Determine size of animal population