Cooperative Fish and Wildlife Research Units Program: New York
Education, Research and Technical Assistance for Managing Our Natural Resources

New York Project

Population Status of Carnivores

August 2011 - August 2016

Personnel

Participating Agencies

U.S. Fish and Wildlife Service

This project will develop models to evaluate population status of select carnivore species, using spatial capture-recapture methods.

Research Publications

Research Publications	Publication Date
Fuller, A.K., C.S. Sutherland, J.A. Royle, and M.P. Hare. 2016. Estimating population density and connectivity of American mink using spatial capture-recapture. Ecological Applications. http://dx.doi.org/10.1890/15-0315.1	April 2016
Sutherland, C., A. K. Fuller, and J.A. Royle. 2014. Modeling non-Euclidean movement and landscape connectivity in highly structured ecological networks. Methods in Ecology and Evolution 6: 169–177. doi: 10.1111/2041-210X.12316 \| Abstract	February 2015	Movement is influenced by landscape structure, configuration and geometry, but measuring distance as perceived by animals poses technical and logistical challenges. Instead, movement is typically measured using Euclidean distance, irrespective of location or landscape structure, or is based on arbitrary cost surfaces. A recently proposed extension of spatial capture-recapture (SCR) models resolves this issue using spatial encounter histories of individuals to calculate least-cost paths (ecological distance: Royle et al. 2013) thereby relaxing the Euclidean assumption. We evaluate the consequences of violating the Euclidean distance assumption when estimating abundance in highly structured landscapes, and demonstrate the value of this approach estimating biologically realistic space-use patterns and landscape connectivity. We simulated SCR data in a riparian habitat network, using the ecological distance model under an range of scenarios where space-use in and around the landscape was increasingly associated with water (i.e. increasingly less Euclidean). To assess the influence of miscalculating distance on estimates of population size, we compared the results from the ecological and Euclidean distance models. We then demonstrate that the ecological distance model can be used to estimate home range geometry when space use is not symmetrical. Finally, we provide a method for calculating landscape connectivity based on modelled species-landscape interactions generated from capture-recapture data. Using ecological distance always produced unbiased estimates of abundance. Explicitly modelling the strength of the species-landscape interaction provided a direct measure of landscape connectivity and better characterised true home range geometry. Abundance under the Euclidean distance model was increasingly (negatively) biased as movement was 30 more strongly associated with water and, because home ranges are assumed to be symmetrical, produced poor characterizations of home range geometry and no information about connectivity. The ecological distance SCR model uses spatially indexed capture-recapture data to estimate how activity patters are be influenced by landscape structure. The approach produces 35 unbiased estimates of abundance, but perhaps more importantly, provides biologically realistic representations of home range geometry and direct information about species-landscape interactions. The incorporation of both structural (landscape) and functional (movement) 38 components of connectivity provides a direct measure species-specific landscape connectivity.

Presentations

Presentations	Presentation Date
Sutherland, C. A.K. Fuller, and J.A. Royle. 2015. Estimating abundance when landscape structure determines patterns of both space-use and density. 22nd Annual Conference of The Wildlife Society. Winnipeg, Manitoba, Canada. 21 October, 2015.	October 2015
Sutherland, C. S., J. A. Royle, and A. K. Fuller. Using stream distance to estimate connectivity, movement and density of American mink in a river network using spatial capture-recapture models. The Wildlife Society 20th Annual Conference, Milwaukee, WI. 9 October, 2013.	October 2013
Sutherland, C., A. K. Fuller, and J. A. Royle. Measuring non-Euclidean movement patterns in structured habitat networks using spatial capture-recapture models. International Statistical Ecology Conference 2014, Montpellier, France. 4 July, 2014.	July 2014
Sutherland, C., A.K. Fuller, and J.A. Royle. Estimating American mink, Neovision vison, density in complex river networks using spatial capture-recapture. 71st Annual Northeast Fish and Wildlife Conference. 21 April, 2015.	April 2015
Sutherland, C., A.K. Fuller, and J.A. Royle. The importance of accounting for biologically realistic movements patterns for abundance estimates using spatial capture-recapture. New York Cooperative Fish and Wildlife Research Unit Coordinating Committee Meeting. September 16, 2014.	September 2014