Abstract
The estimation of demographic parameters is a key component of
evolutionary demography and conservation biology. Capture-mark-recapture
methods have served as a fundamental tool for estimating demographic
parameters. The accurate estimation of demographic parameters in
capture-mark-recapture studies depends on accurate modeling of the
observation process. Classic capture-mark-recapture models typically
model the observation process as a Bernoulli or categorical trial with
some detection probability conditional on a marked individual’s
availability for detection (e.g., alive, or alive and present in a study
area). Alternatives to this approach are underused, but may have great
utility in capture-recapture studies. In this paper we explore a simple
concept: in the same way that counts contain more information about
abundance than simple detection/non-detection data, the number of
encounters of individuals during observation occasions contain more
information about the observation process than detection/non-detection
data for individuals during the same occasion. Rather than using
Bernoulli or categorical distributions to estimate detection
probability, we demonstrate the application of zero-inflated Poisson and
gamma-Poisson distributions. This allows for inference on availability
for encounter (i.e., temporary emigration), as well as a wide variety of
parameterizations for heterogeneity in the observation process. We
demonstrate that this approach can accurately recover demographic and
observation parameters in the presence of individual heterogeneity in
detection probability, and discuss some potential future extensions of
this method.