Estimating carnivore community structures

Abstract

Obtaining reliable estimates of the structure of carnivore communities is of paramount importance because of their ecological roles, ecosystem services and impact on biodiversity conservation, but they are still scarce. This information is key for carnivore management: to build support for and acceptance of management decisions and policies it is crucial that those decisions are based on robust and high quality information. Here, we combined camera and live-trapping surveys, as well as telemetry data, with spatially-explicit Bayesian models to show the usefulness of an integrated multi-method and multi-model approach to monitor carnivore community structures. Our methods account for imperfect detection and effectively deal with species with non-recognizable individuals. In our Mediterranean study system, the terrestrial carnivore community was dominated by red foxes (0.410 individuals/km2); Egyptian mongooses, feral cats and stone martens were similarly abundant (0.252, 0.249 and 0.240 individuals/km2, respectively), whereas badgers and common genets were the least common (0.130 and 0.087 individuals/km2, respectively). The precision of density estimates improved by incorporating multiple covariates, device operation, and accounting for the removal of individuals. The approach presented here has substantial implications for decision-making since it allows, for instance, the evaluation, in a standard and comparable way, of community responses to interventions.

Spatial and temporal patterns in age structure of Golden Eagles wintering in eastern North America

“…Use of motion‐sensitive trail cameras was, early in the development of the technology, frequently applied to the study of mammals (Kelly , Ahumada et al , Jiménez et al ). However, in recent years several camera‐trapping studies have focused on birds (Luo et al , Roncol et al ).…”

Estimating abundances, densities, and interspecific associations in a carnivore community

“…This was a consequence of not having detections of marked foxes, meaning that we could not use an SMR model for this species. Spatial capture‐recapture studies should attempt to obtain detection information from at least some marked individuals for all species (e.g., using genetic sampling methods, physically marking some individuals; Jiménez et al ). The SUN model used in this study should be used as a last resort if detections from marked individuals cannot be obtained (Chandler and Royle , Ramsey et al ).…”

“…If cameras are spaced too widely then too few individuals are detected at multiple locations, and if cameras are spaced too narrowly then too few individuals will be sampled; both scenarios can generate considerable imprecision in the estimates of the spatial scale parameter, . Prior information on home range sizes should be used to determine the spacing of camera locations in a study aiming to estimate the abundances, densities, and activity centers of multiple carnivore species (Sollmann et al , Chandler and Royle , Jiménez et al ). Simulations indicate that the SUN model produces unbiased estimates of abundance and density if camera spacing is less than the radial length of a typical home range and the number of encounter occasions is ≥10 (Ramsey et al ).…”

“…A major advantage of using camera traps in an array is that they can detect multiple species, providing an opportunity to characterize community structure in terms of the abundances and densities of the species present (O’Brien and Kinnaird , Jiménez et al ). As noted above, another component of community structure is spatial overlap (i.e., do species tend to associate or dissociate?).…”

The importance of considering multiple interacting species for conservation of species at risk

“…Fortunately, recent advances in both field and statistical techniques can improve abilities to estimate population densities through the use of camera trap surveys and Bayesian spatial‐capture‐recapture (SCR) models (e.g., Chandler & Royle ; Jiménez et al. ; Burgar et al. ).…”