Estimating mammalian species richness and occupancy in tropical forest canopies with arboreal camera traps

Abstract

Large and medium-bodied rainforest canopy mammals are typically surveyed using line transects, but these are labour intensive and usually ignore nocturnal species. Camera traps have become the preferred tool for assessing terrestrial mammal communities, but have rarely been used for arboreal species. Here, we compare the efficiency of arboreal camera trapping with line transects for inventorying medium and large-sized arboreal mammals, and assess the viability of using camera traps in trees to model habitat occupancy. We installed 42 camera traps, spaced 2 km apart, in the canopy of the Maijuna-Kichwa Regional Conservation Area, Peru and walked 2014 km of diurnal line transects on 22 trails at the same site. We compared the efficiency of each method using species accumulation curves. We applied a multi-species occupancy model, while examining the effect of camera height on detection probabilities, including the distance from a village and from a river as covariates to examine variability in habitat occupancy. In 3147 camera days, 18 species of arboreal medium and large-sized mammals were detected by cameras, while 11 species were recorded on line transects. Ten of these species were detected by both methods. Diurnal species were detected more quickly and with less effort using arboreal camera trapping than using diurnal line transects at the same site, although some species were more easily detected during line transects. Habitat occupancy was positively correlated with distance from the village for two species, and negatively correlated with distance from the river for one. Detection probabilities increased modestly with camera height. Practical limitations of arboreal camera trapping include the requirement for specialized climbing techniques, as well as increased potential for false triggers, requiring extended processing time. Arboreal camera trapping is an efficient method for inventorying arboreal mammals and a viable option for studying their distribution relative to environmental or anthropogenic variables when abundance or density estimates are not required. 146

Camera traps as a tool for Carnivore conservation in a mosaic of Protected Areas in the Pantanal wetlands, Brazil

“…Furthermore, studies have also demonstrated the potential of this tool for recording and studying arboreal and aquatic species, such as marsupials, rodents and primates (Oliveira-Santos et al, 2008;Leuchtenberger et al, 2014;Bowler et al, 2017). As camera traps were set in trails, some species of carnivores were favoured in terms of detection, as crab-eating foxes, ocelots and jaguars (Tobler et al, 2008;Harmsen et al, 2010).…”

Human disturbance impacts on rainforest mammals are most notable in the canopy, especially for larger‐bodied species

“…Here, we use both arboreal and terrestrial camera traps to directly compare the response of arboreal and terrestrial mammal communities to rainforest disturbance. While the benefits of terrestrial camera traps for understanding community‐level responses have been well documented (Rowcliffe & Carbone, ; Srbek‐Araujo & Chiarello, ; Tobler, Carrillo‐Percastegui, Leite Pitman, Mares, & Powell, ; Tobler, Carrillo‐Percastegui, Zúñiga Hartley, & Powell, ; Tobler, Hartley, Carrillo‐Percastegui, & Powell, ), only recently has arboreal camera trapping become feasible at greater scale; thanks to improvements in battery life, reduced cost and memory capacity (Bowler et al, ; Whitworth et al, ). Consequently, to date there have been no direct comparisons using camera traps to test whether terrestrial and canopy mammal communities respond to rainforest disturbance in a similar way—although previous work has compared arboreal camera trapping with terrestrial transects (e.g., Bowler et al, , Whitworth et al, ).…”

“…While the benefits of terrestrial camera traps for understanding community‐level responses have been well documented (Rowcliffe & Carbone, ; Srbek‐Araujo & Chiarello, ; Tobler, Carrillo‐Percastegui, Leite Pitman, Mares, & Powell, ; Tobler, Carrillo‐Percastegui, Zúñiga Hartley, & Powell, ; Tobler, Hartley, Carrillo‐Percastegui, & Powell, ), only recently has arboreal camera trapping become feasible at greater scale; thanks to improvements in battery life, reduced cost and memory capacity (Bowler et al, ; Whitworth et al, ). Consequently, to date there have been no direct comparisons using camera traps to test whether terrestrial and canopy mammal communities respond to rainforest disturbance in a similar way—although previous work has compared arboreal camera trapping with terrestrial transects (e.g., Bowler et al, , Whitworth et al, ). In this study, we use multispecies occupancy models, which are well suited to analysis of camera data at the community level (Tobler et al, ) and for assessing species‐specific responses to varying levels of forest disturbance (Bowler et al, ; Sollmann et al, ; Tobler et al, ), to answer the question of whether arboreal rainforest mammals show a greater sensitivity to forest habitat degradation compared with their terrestrial counterparts.…”

“…Consequently, to date there have been no direct comparisons using camera traps to test whether terrestrial and canopy mammal communities respond to rainforest disturbance in a similar way—although previous work has compared arboreal camera trapping with terrestrial transects (e.g., Bowler et al, , Whitworth et al, ). In this study, we use multispecies occupancy models, which are well suited to analysis of camera data at the community level (Tobler et al, ) and for assessing species‐specific responses to varying levels of forest disturbance (Bowler et al, ; Sollmann et al, ; Tobler et al, ), to answer the question of whether arboreal rainforest mammals show a greater sensitivity to forest habitat degradation compared with their terrestrial counterparts.…”

Born‐digital biodiversity data: Millions and billions

“…As a photo‐vouchered spatial record of biodiversity, camera traps offer a direct parallel to the museum mammal specimen because the identity of the species can be verified in the photograph, potentially even automatically through artificial intelligence (He et al, ). Although not all species can be visually distinguished (Potter, Brady, & Murphy, ), camera traps are useful for most medium or large terrestrial mammals and have recently proven effective for small mammals and canopy fauna (Bowler, Tobler, Endress, Gilmore, & Anderson, ; McCleery et al, ). Camera traps also have the advantage of clearly recording sampling effort (where they are run and for how long), which is typically not known for museum collections or citizen science observations.…”