Uniform performance of mammal detection methods under contrasting environmental conditions in Mediterranean landscapes

Abstract

Monitoring local occupancy and the regional distribution of wild mammals is essential to guide species management and set conservation priorities. However, variables such as weather, substrate hardness, or habitat characteristics may indirectly affect the performance of the methods employed for monitoring mammal occurrence. Little information exists about the influence of spatio-temporal factors on the performance of survey methods and its implications for mammal monitoring. Using data from a heterogeneous region in the Guadiamar River basin, SW Spain, which encompass forest, agricultural, and mosaic landscapes, we (1) explore whether four widely used detection methods, namely camera traps, scent stations, track surveys, and scat surveys, differ in efficiency; (2) test the hypothesis that spatio-temporal factors do not affect method efficiency; and (3) examine the effect of landscape on the replication effort needed to detect target species. After controlling for variation in mammal occurrence across space and over time, the interaction between spatio-temporal factors and detection methods was not significant. Likewise, we found a negligible influence of landscape type on the replication effort needed to detect species actually present. When compared to camera traps, scent stations, and scat surveys, track surveys were the most efficient and fastest methodology for surveying mammals in our study landscapes. Monitoring programs of mammal occurrence are often applied to broad and heterogeneous regions and/or during extended periods. Therefore, survey methods should describe not only spatio-temporal variation in mammal abundance or activity but also maintain high detection efficiency in a variety of environmental conditions. The detection efficiency of each survey method changed little regardless of considerable environmental variation, making more reliable the marked differences between methods in their ability to detect target species. We recommend accounting for the effect of spatio-temporal factors as potential sources of variation in order to test whether our results can be generalized and to increase the quality of large-scale monitoring of mammal occurrence.

Social perception of mesocarnivores within hunting areas differs from actual species abundance

“…In hunting areas with two or more sampling units, they were 2 km apart from each other to promote spatial independence between them. The regular performance and high efficiency of track and scat surveys have been proven in other Mediterranean regions with similar land covers [ 30 , 31 ]. Therefore, we simultaneously carried out track surveys and scat surveys to estimate the relative abundance of mesocarnivores and small game species within each sampling unit.…”