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Spatial capture-recapture models for search-encounter data
Article first published online: 18 MAY 2011
© 2011 The Authors. Methods in Ecology and Evolution © 2011 British Ecological Society
Methods in Ecology and Evolution
Volume 2, Issue 6, pages 602–611, December 2011
How to Cite
Royle, J. A., Kéry, M. and Guélat, J. (2011), Spatial capture-recapture models for search-encounter data. Methods in Ecology and Evolution, 2: 602–611. doi: 10.1111/j.2041-210X.2011.00116.x
- Issue published online: 5 DEC 2011
- Article first published online: 18 MAY 2011
- Received 5 July 2010; accepted 3 April 2011 Handling Editor: Nigel Yoccoz
- Bayesian analysis;
- data augmentation;
- density estimation;
- distance sampling;
- hierarchical models;
- population size;
- search-encounter data;
- spatial capture–recapture;
- spatially explicit capture–recapture
1. Spatial capture–recapture models make use of auxiliary data on capture location to provide density estimates for animal populations. Previously, models have been developed primarily for fixed trap arrays which define the observable locations of individuals by a set of discrete points.
2. Here, we develop a class of models for ‘search-encounter’ data, i.e. for detections of recognizable individuals in continuous space, not restricted to trap locations. In our hierarchical model, detection probability is related to the average distance between individual location and the survey path. The locations are allowed to change over time owing to movements of individuals, and individual locations are related formally by a model describing individual activity or home range centre which is itself regarded as a latent variable in the model. We provide a Bayesian analysis of the model in WinBUGS, and develop a custom MCMC algorithm in the R language.
3. The model is applied to simulated data and to territory mapping data for the Willow Tit from the Swiss Breeding Bird Survey MHB. While the observed density was 15 territories per nominal 1 km2 plot of unknown effective sample area, the model produced a density estimate of 21·12 territories per square km (95% posterior interval: 17–26).
4. Spatial capture–recapture models are relevant to virtually all animal population studies that seek to estimate population size or density, yet existing models have been proposed mainly for conventional sampling using arrays of traps. Our model for search-encounter data, where the spatial pattern of searching can be arbitrary and may change over occasions, greatly expands the scope and utility of spatial capture–recapture models.