Using the mark-recapture equation what factors can cause an overestimate of population size and what factors...

Using the mark-recapture equation what factors can cause an overestimate of population size and what factors will cause an underestimate of population size?

Expert Solution

The mark-recapture method is a good technique to estimate an animal's population size. The equation is as follows.

where, K = the no. of animals captured second time.
n = the no. of animals marked first time
k = the no. of animals marked recaptured animals
N = the total no. of animals

However, certain factors that violate the assumptions of the technique may lead to over-estimation or under-estimation of population size.

If the animals are affected by 'marking' in the form of life expectancy and behaviour, or they do not mix in the population properly, the researcher may be unable to recapture these marked animals. This would decrease the value of k, leading to overestimation.
If the time interval between two markings is large, the overall population may increase, leading to a higher number of animals captured on the second visit which are unmarked, increasing the value of K in comparison with k, causing overestimation.
Also, if the mark is lost, or the marking is improper, the same animal may be marked twice, again leading to overestimation of N.

On the other hand, if the marked animals do not mix in the population properly, they have a higher chance to be recaptured, greatly increasing the value of k, leading to underestimation.
This problem may get compounded by the reduction in value of K due to poor sampling, which would also lead to underestimation of population size.

gladiator answered 1 year ago

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