Review of field methods for monitoring Asian bears

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

“…We used a 4 × 4 km grid cell size based on known female range areas and a 8 × 8 km grid cell size for the remaining part of the study area, with one baited station placed in each grid cell. Hair traps were placed in the best predicted bear habitat, considering topography and accessibility by 4-wheel drive vehicles, a maximum of 10 min walk from the vehicle and bear expert opinion (tree types or tree species, with characteristics that make them more conspicuous for rubbing; González-Bernardo et al 2021; Proctor et al 2022). Sites were visited once every 15 days from May to September for sample collection and lure replacement. Systematic by camera traps (SCT), corresponding to cameras (Leaf river Outdoor, HCO Soutguard SG 550 and Uway Nicht Trakker until 2013, and Bushnell Trophy Cam or NatureView HD and Reconyx HC600 or XR6 after 2013) equipped with movement detection that were fixed on trees in areas with frequent animal passage away from the walked transects and that were associated nearby with hair traps similar to the ones used for the systematic by trails method (Burton et al 2015; Parres et al 2020; see Fig.…”

“…The average home range size (Kernel 85%) of brown bears in the Pyrenees (excluding recently translocated individuals) was 84 km² for adult females (N = 6) and 1,551 km² for adult males (N = 6) (Halotel 2022; similar to the average home range of radio-collared adult bears in similar Eurasian regions: Huber & Roth 1993;Mertzanis et al 2005;Gavrilov et al 2015).We used a 4 x 4 km grid cell size based on known female range areas and a 8 x 8 km grid cell size for the remaining part of the study area, with one baited station placed in each grid cell. Hair traps were placed in the best predicted bear habitat, considering topography and accessibility by 4-wheel drive vehicles, a maximum of 10 min walk from the vehicle and bear expert opinion (tree types or tree species, with characteristics that make them more conspicuous for rubbing; González-Bernardo et al 2021;Proctor et al 2022). Sites were visited once every 15 days from May to September for sample collection and lure replacement.…”

“…Invasive physical tagging-based methods are difficult to implement, so population monitoring consequently often needs to rely on non-invasive sampling methods (Long & Zielinski 2008; Thompson 2013). Among them, molecular tools and camera trapping are now commonly used methods (e.g., Forsyth et al 2022; Piel et al 2022; Proctor et al 2022). For species lacking unique natural individual patterns that can be identified from photos, non-invasive genotyping of DNA extracted from animal hair or scat often remains the most practical solution to estimate population abundance (Waits & Paetkau 2005).…”

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

“…The average home range size (Kernel 85%) of brown bears in the Pyrenees (excluding recently translocated individuals) was 84 km² for adult females (N = 6) and 1,551 km² for adult males (N = 6) (Halotel 2022; similar to the average home range of radio-collared adult bears in similar Eurasian regions: Huber & Roth 1993;Mertzanis et al 2005;Gavrilov et al 2015).We used a 4 x 4 km grid cell size based on known female range areas and a 8 x 8 km grid cell size for the remaining part of the study area, with one baited station placed in each grid cell. Hair traps were placed in the best predicted bear habitat, considering topography and accessibility by 4-wheel drive vehicles, a maximum of 10 min walk from the vehicle and bear expert opinion (tree types or tree species, with characteristics that make them more conspicuous for rubbing; González-Bernardo et al 2021;Proctor et al 2022). Sites were visited once every 15 days from May to September for sample collection and lure replacement.…”

“…Invasive physical tagging-based methods are difficult to implement, so population monitoring consequently often needs to rely on non-invasive sampling methods (Long & Zielinski 2008;Thompson 2013). Among them, molecular tools and camera trapping are now commonly used methods (e.g., Forsyth et al 2022;Piel et al 2022;Proctor et al 2022). For species lacking unique natural individual patterns that can be identified from photos, non-invasive genotyping of DNA extracted from animal hair or scat often remains the most practical solution to estimate population abundance (Waits & Paetkau 2005).…”