Introduction to Mark-Recapture Sampling and Closed-Population Models - Introduction to Ecological Sampling - page 87

7
Introduction to Mark-Recapture Sampling
and Closed- Population Models
Jorge Navarro, Bryan Manly, and Roberto Barrientos-Medina
7.1 Introduction
A critical issue in many ecological studies is the estimation of population
abundance, whether the population is animals or plants. This becomes
particularly important in the case of animal populations because of their
mobility. If we combine the interest in knowing the population size with
determining which forces operate on it, then we must recognize the impor-
tance of methodological tools that help us effectively meet these tasks.
The methods commonly used to estimate the abundance of animal pop-
ulations include marking, releasing, and recapturing of individuals, pro-
cesses that in most cases are repeated several times. For this reason, they
are called mark-recapture or capture-recapture methods. In general, these
techniques allow us to estimate the size of an animal population by cap-
turing the individuals that have been previously marked (Williams et al.,
2002). Mark-recapture methods are also valuable for estimating the density
of populations, that is, the number of organisms present per unit area.
The first applications of these principles were by John Graunt and Simon
Laplace (both working with human populations), but C.G.J. Petersen (a fish-
eries biologist) made the first ecological application in 1896. Other historical
applications of these methods include the estimation of the abundance of
ducks made by Lincoln in 1930 and the study by Jackson in 1933 to estimate the
abundance of insect populations (Williams et al., 2002; Amstrup et al . , 2005).
The first part of this chapter covers some basic mark-recapture terminology
useful for ecologists interested in the study of animal populations. A crucial
feature that is important to identify in any study is whether the sampled
population is closed or open, where closed means that the abundance does
not change with time and open means that animals may enter and leave the
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