NOREMARK: Population Estimation from Mark-Resighting Surveys
Publication Type: |
Journal Article |
Year of Publication: |
1996 |
Authors: |
Gary C. White |
Publication/Journal: |
Wildlife Society Bulletin |
Keywords: |
closure, ightings urveys, lincoln-petersenm, mark-resight, maximum likelihood, p opulatione stimations |
Abstract:
Estimation of population size of a geographically and demographically closed but free-ranging population is a common problem encountered by wildlife biologists. The earliest approaches to this problem were developed by Petersen in 1896 and later by Lincoln in 1930, where capture-recapture techniques were applied. Extensions to the simple 2 occasion Lincoln-Petersen estimator were developed for multiple occasions (Schnabel 1938, Darroch 1958), for removal experiments (Zippin 1956, 1958), and for heterogeneity
of individual animals (Burnham and Overton 1978, 1979, Chao 1988). For the capture-recapture technique, Otis et al. (1978) and White et al. (1982) summarized available methods, and others (White et al. 1978, Rexstad and Bumham 1991) described the program CAPTURE for computing these estimators of population size. More technologically advanced approaches to abundance estimation have incorporated animals marked with radio transmitters. The initial sample of animals is captured and marked with radios, but recaptures of these animals are obtained by observation, not actually recapturing them. The limitation of this procedure is that unmarked animals are not marked on subsequent occasions. The advantage of this procedure is that resightings are generally much
cheaper to acquire than physically capturing and handling the animals. The mark-resight procedure has been tested with known opulations of mule deer (Odocoileus bemionus; Bartmann et al. 1987) and used with white-tailed deer (O. virginianus; Rice and
Harder 1977), mountain sheep (Ovis canadensis; Furlow et al. 1981, Neal et al. 1993), black bear (Ursus americanus) and grizzly bear (U. arctos; Miller et al. 1987), and coyote (Canis latrans; Hein 1992). Arnason et al. (1991) described a method in which the number of marked animals is not known, whereas the mark-resight estimators described here assume the number of marked animals is known. Program NOREMARKco mputes 4 mark-resight estimators of population abundance, modeling variation of sighting probabilities across time, individual heterogeneity of sighting probabilities, or immigration and emigration from a fixed study area (Eberhardt 1990). For all 4 estimators, the marked animals are assumed to have been drawn randomly from the population (i.e., marked animals are a representative sample from the population).