Populations - Capture Recapture

Question 1

Technique for estimating pop size for animals that move

Answer 1

Capture-Mark-Recapture

Question 2

S1

Answer 2

Sample of individuals caught, counted and marked

Released back into original location and allowed to mix with unmarked individuals

Question 3

S2

Answer 3

After being allowed to mix with unmarked - second sample caught and counted

Number of marked individuals noted

Question 4

r

Answer 4

Recaptures

Marked individuals in S2

Question 5

Lincoln Index/ Peterson Estimate

Answer 5

Question 6

Method of Capture for Small GroundSpecies

Answer 6

Pitfall Trap

Marked by correction fluid or quick drying waterproof paint

Question 7

Assumptions for Mark

Answer 7

Should not harm animal (tested by keeping sample of marked indis in lab to check toxicity)

Should persist over sampling period

Should not make animal more obv to predators

Should not influence behaviour

If req met - prob capturing marked should be same as capturing any member of pop

Question 8

Assumption of Time

Answer 8

Marked individuals completely mixed in pop

Enough time elapsed between visits to the study area to allow this to happen

Question 9

Assumption of Im/Emigration

Answer 9

No significant gains or loses

Avoided by sampling a pop isolated from other pops and ensuring two visits are close enough in time

Question 10

Assumption Of Births and Deaths

Answer 10

No significant gains or losses

If above req met then proportion of marked individuals in second sample is equivalent to proportion of marked individuals in whole pop

Question 11

For estimate to be reliable

Answer 11

Large sample should be marked initially

Between 10-30% of population