Methods for the estimation of population parameters by capture-mark-recapture

Abstract

The conclusions of studies on population ecology are just as reliable as the estimates of the parameters on which they are based. Nevertheless, many population ecologists, in Brazil and abroad, do not take advantage of the efficient methods available to estimate population parameters by Capture-Mark­-Recapture (CMR). This review aims to help bringing those methods to the ecologists. For closed populations ­which vary during the sampling period - there is a wide variety of methods to estimate population size (N), including some quite sophisticated ones, which are able to deal with CMR's most serious problem: unequal catchability within the population. The methods for open populations (the ones which vary along the sampling period) allow estimation of mortality and recruitment rates - besides N - by relaxing the assumption of closed population. On the other hand, open population methods pay the price of lower sophistication and precision in estimating N. The use of Pollock's "robust design", which combines the advantages of open and closed population methods, is recommended. Having N, estimating population density for non-sessile organisms is far from obvious, but several methods based on movement patterns are available. For estimating home range areas, a compromise is needed. Mapping methods represent home ranges with less detail than Utilization Distribution methods. On the other hand, the latter require amounts of data which are seldom available in field studies, except using radiotelemetry, a technique which also brings its own problems.