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population between sample times. Historically, the theory of closed mark-
recapture methods was developed first, and it concerned less-sophisticated
procedures in comparison to open-population models. Thus, this chapter
focuses on mark-recapture methods applicable to closed populations, with
open-population models covered in Chapter 8. Good references for the mate-
rial reviewed in this chapter and Chapter 8, and for more advanced meth-
ods, are the work of Otis et al. (1978), White et al
.
(1982), Pollock et al
.
(1990),
Williams et al
.
(2002), and Amstrup et al
.
(2005).
7.2 Terminology and Assumptions
Important concepts related to mark-recapture methods are as follows:
1. The sampling method. Mark-recapture methods involve taking a
series of samples of the population under study, separated by one
or more days or weeks, which in practice means any discrete time
intervals.
2. The type of population. An important aspect of the selection of a
method for the analysis of data is the type of population under study,
which is assumed to be either closed or open. As noted, a closed
population is one in which the population size does not change
appreciably during the study period so that any gains through births
and immigration or losses through mortality and emigration in the
population are assumed to be minimal. In contrast with open popu-
lations, the population size changes throughout the study period.
3. The type of marking. There are three types of marks. The most natu-
ral mark is affixed, clipped, painted, and the like on each individual
so that it can be identified if it is recaptured. The second type of
mark is date or sample specific, indicating how many times the ani-
mal was captured throughout the study. Finally, there is the less-
specific mark, which simply allows the separation between labeled
and unlabeled animals and thereby provides a minimum amount of
information. One aspect that should be kept in mind is the fact that
the marking should not jeopardize the survival of an animal.
4. The covariates. Mark-recapture sampling may be used in a wide
range of research goals involving the estimation of population
parameters, where these may be ascribed to differences in indi-
viduals' characteristics (e.g., age, sex, habitat, or body weight) or
particular incidents (e.g., catastrophic events like hurricanes). Thus,
covariate recording might be crucial for the mark-recapture process.
