Hierarchical models for estimating density from DNA mark-recapture studies.
Genetic sampling is increasingly used as a tool by wildlife biologists and managers to estimate abundance and density of species. Typically, DNA is used to identify individuals captured in an array of traps (e.g., baited hair snares) from which individual encounter histories are derived. Standard methods for estimating the size of a closed population can be applied to such data. However, due to the movement of individuals on and off the trapping array during sampling, the area over which individuals are exposed to trapping is unknown, and so obtaining unbiased estimates of density has proved difficult. We propose a hierarchical spatial capture-recapture model which contains explicit models for the spatial point process governing the distribution of individuals and their exposure to (via movement) and detection by traps. Detection probability is modeled as a function of each individual's distance to the trap. We applied this model to a black bear (Ursus americanus) study conducted in 2006 using a hair-snare trap array in the Adirondack region of New York, USA. We estimated the density of bears to be 0.159 bears/km2, which is lower than the estimated density (0.410 bears/km2) based on standard closed population techniques. A Bayesian analysis of the model is fully implemented in the software program WinBUGS.
Gardner
Beth
B
U.S. Geological Survey, Patuxent Wildlife Research Center, Laurel, Maryland 20708, USA. bgardner@usgs.gov
Royle
J Andrew
JA
Wegan
Michael T
MT
D000818:Animals; D004247:DNA / Q000032:analysis* / Q000235:genetics*; D017753:Ecosystem; D006197:Hair / Q000737:chemistry*; D008954:Models, Biological; D009518:New York; D011156:Population Density; D012107:Research Design; D001503:Ursidae / Q000235:genetics* / Q000502:physiology
D004247:DNA