Question

a) in mark and recapture method, how does the variation in values of N (estimated size) change as a function of the size of the recapture sample (when we increase the recapture sample)?

b) what is the general effect of recapture effort on the variability associated with population size estimates in mark-recapture studies?

Answer 1

a) In mark and recapture method the variation in values of N (estimated size) may differ due to the size of recaptured sample. When we capture and mark some individuals they may be or may not be dispersed with the time. If we recaptured some individuals for calculating the estimated size of the population, they may not be dispersed. So we easily go to the calculation that most of the individuals are caught by recapture, hence population size is small. But if we take larger size of recapture sample, the sampling errors will be less. So we can be more close to the real value of estimated size of a population.

b) The recapture effort has a massive role on the variability of the population size. Recapture effort may be seasonal or spatial. Support we capture some migratory birds in India in the winter season and mark them. At spring most of them are out to their summer habitat. At summer we recapture some of them, the sample size will be small as maximum of them have leave the country. So there must be a chance of sampling errors. The estimated size of the population may be differ for this recapture effort at summer.