A unifying model for capture-recapture and distance sampling surveys of wildlife populations

Spatially explicit capture-recapture (SECR) methods extend traditionalcapture-recapture methods for estimating population density by using information contained in the location of traps. The The central feature of theimprovement is estimation from the locations of traps at which animals wereand were not captured to estimate of the distance over which animals aresusceptible to capture. We show that standard SECR models are a special case of a more general class of model in which animal detection is not certain, but someinformation is available about the location of detected animals. The model classaccommodates a range of spatial data types and includes as a special casemark-recapture distance sampling, where distances to detected animals arerecorded by multiple observers. Other examples of additional informationthat can be included are bearing to detected animals, strength of acousticsignals received from detected animals, and time of arrival of acoustic signalsat detectors. Errors in variables are easily incorporated. We illustrate the versatility of the model and method through a number of applications, in each case using real and simulated data, and comparing our results with those from previous studies where these are available.