Skip to main content
Article
Likelihood analysis of spatial capture-recapture models for stratified or class structured populations
Ecosphere (2015)
  • J. Royle
  • Chris Sutherland, University of Massachusetts - Amherst
  • Angela Fuller
  • Catherine Sun
Abstract
We develop a likelihood analysis framework for fitting spatial capture-recapture (SCR) models to data collected on class structured or stratified populations. Our interest is motivated by the
necessity of accommodating the problem of missing observations of individual class membership. This is particularly problematic in SCR data arising from DNA analysis of scat, hair or other material, which
frequently yields individual identity but fails to identify the sex. Moreover, this can represent a large fraction of the data and, given the typically small sample sizes of many capture-recapture studies based on DNA information, utilization of the data with missing sex information is necessary. We develop the class structured likelihood for the case of missing covariate values, and then we address the scaling of the likelihood so that models with and without class structured parameters can be formally compared regardless of missing values.We apply our class structured model to black bear data collected in New York in which sex could be determined for only 62 of 169 uniquely identified individuals. The models containing
sex-specificity of both the intercept of the SCR encounter probability model and the distance coefficient, and including a behavioral response are strongly favored by log-likelihood. Estimated population sex ratio is strongly influenced by sex structure in model parameters illustrating the importance of rigorous modeling of sex differences in capture-recapture models.
Keywords
  • capture-recapture,
  • categorical covariates,
  • class structure,
  • density,
  • missing data,
  • sex assignment,
  • spatial capture-recapture,
  • stratified populations
Disciplines
Publication Date
Winter February 12, 2015
DOI
10.1890/ES14-00148.1
Citation Information
Royle, J. A., C. Sutherland, A. K. Fuller, and C. C. Sun. 2015. Likelihood analysis of spatial capture-recapture models for stratified or class structured populations. Ecosphere 6(2):22. http://dx.doi.org/10.1890/ES14-00148.1