A computer program for capture-recapture studies of animal populations ; a Fortran listing for the stochastic model of G. M. Jolly

Abstract

White (1971) briefly describes the versatility of a Fortran computer program which analyses capture-recapture data from animal populations, using the stochastic model of G. M. Jolly (1965) . The listing and a fuller description are now given.

The program is applicable to studies in which marked animals are individually recognisable, although White (1971) suggests two ways in which to adapt data from studies in which animals are not individually recognisable. The program is in five sections which store all the capture-recapture records and then organise any given selections of these data into trellis tables and the tables of derived population estimates. Data can be used from studies with or without intermediate recapture samples (described by Jolly (1965)), and any selection of consecutive data can be analysed separately for any subpopulation. To permit such a selection, the migration of marked animals (as well as unmarked) between sub-populations is accounted for, both in space and time, but in such applications there should be no repeated to-and-fro migration since a basic assumption of Jolly's model is that all emigration is permanent. Certain restrictions can be placed upon the analysis of data and animals can be added to or withdrawn from the population during a study.

The program is written in Fortran IV and was compiled and tested on an 8K IBM 1130 computer using the IBM 1130 Monitor Fortran.