Integrating opportunistic and structured non-invasive surveys with spatial capture-recapture models to map connectivity of the Pyrenean brown bear population

International audienceConnectivity, in the sense of the persistence of movements between habitat patches, is key to maintain endangeredpopulations and has to be evaluated in management plans. In practice, connectivity is difficult to quantifyespecially for rare and elusive species. Here, we use spatial capture-recapture (SCR) models with an ecologicaldetection distance to identify barriers to movement. We focused on the transnational critically endangeredPyrenean brown bear (Ursus arctos) population, which is distributed over Spain, France and Andorra and isdivided into two main cores areas following translocations. We integrate structured monitoring from cameratraps and hair snags with opportunistic data gathered after depredation events. While structured monitoringfocuses on areas of regular bear presence, the integration of opportunistic data allows us to obtain information ina wider range of habitat, which is especially important for ecological inference. By estimating a resistanceparameter from encounter data, we show that the road network impedes movements, leading to smaller homeranges with increasing road density. Although the quantitative effect of roads is context-dependent (i.e. varyingaccording to landscape configuration), our model predicts that a brown bear with a home range located in anarea with relatively high road density (8.29 km/km2) has a home range size reduced by 1.4-fold for males and1.6-fold for females compared to a brown bear with a home range located in an area with low road density (1.38km/km2). When assessing connectivity, spatial capture-recapture modeling offers an alternative to the use ofexperts’ opinion when telemetry data are not available

Estimating abundance of a recovering transboundary brown bear population with capture-recapture models

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