A standardized assessment of forest mammal communities reveals consistent functional composition and vulnerability across the tropics

Abstract

The understanding of global diversity patterns has benefitted from a focus on functional traits and how they relate to variation in environmental conditions among assemblages. Distant communities in similar environments often share characteristics, and for tropical forest mammals, this functional trait convergence has been demonstrated at coarse scales (110–200 km resolution), but less is known about how these patterns manifest at fine scales, where local processes (e.g. habitat features and anthropogenic activities) and biotic interactions occur. Here, we used standardized camera trapping data and a novel analytical method that accounts for imperfect detection to assess how the functional composition of terrestrial mammal communities for two traits – trophic guild and body mass – varies across 16 protected areas in tropical forests and three continents, in relation to the extent of protected habitat and anthropogenic pressures. We found that despite their taxonomic differences, communities generally have a consistent trophic guild composition, and respond similarly to these factors. Insectivores were found to be sensitive to the size of protected habitat and surrounding human population density. Body mass distribution varied little among communities both in terms of central tendency and spread, and interestingly, community average body mass declined with proximity to human settlements. Results indicate predicted trait convergence among assemblages at the coarse scale reflects consistent functional composition among communities at the local scale, suggesting that broadly similar habitats and selective pressures shaped communities with similar trophic strategies and responses to drivers of change. These similarities provide a foundation for assessing assemblages under anthropogenic threats and sharing conservation measures.

Camera Trapping to Assess Status and Composition of Mammal Communities in a Biodiversity Hotspot in Myanmar

“…There is a need to understand the priority area for conservation and key species on which to concentrate efforts. Documenting the status of two mammal communities in a poorly studied country like Myanmar, we found patterns that were comparable with other studies in tropical forest communities in terms of the number of species [ 13 , 32 , 47 ]. Surprisingly, we found two similar communities in terms of shared species (22), despite the distance between the two study areas, with only a few differences depending on different geographical ranges.…”

“…One of the most evident results is that degraded or altered forests host a lower diversity in mammal communities [ 3 , 8 , 9 , 10 ]. In recent years, many studies have focused on species richness and persistence/colonization rates to understand diversity patterns in different communities [ 11 , 12 , 13 ] while also considering some functional traits like trophic niches (e.g., diet) and body mass size as indicators of the status of the community [ 14 ]. These indicators could reveal how animals respond to changes (e.g., body mass) or which role a species has in ecosystem functions (e.g., trophic niches) [ 15 ], thus allowing for the understanding of possible alterations and vulnerabilities within different communities [ 16 , 17 ].…”

“…These indicators could reveal how animals respond to changes (e.g., body mass) or which role a species has in ecosystem functions (e.g., trophic niches) [ 15 ], thus allowing for the understanding of possible alterations and vulnerabilities within different communities [ 16 , 17 ]. Recent studies have demonstrated that mammal communities with similar environmental conditions (e.g., habitat and climate) show consistent composition in functional traits and respond similarly to drivers of change, even hosting taxonomically different species [ 13 , 18 ].…”

“…Using a hierarchical modeling framework with a Bayesian formulation [ 28 , 29 ], we focused on the estimation (while accounting for imperfect detections [ 28 ]) of the following parameters: (1) estimated species richness for the whole community used as a proxy of species diversity and representing the most direct measurement of biodiversity [ 30 ] and (2) estimated species richness and proportion within the community of two important functional traits such as trophic niches and body mass. These two traits were largely used in these models to evaluate the general community functional composition [ 13 , 31 , 32 ]. Finally, we also focused on (3) multi-season occupancy estimates since this parameter is widely used as a proxy for population density that often is difficult, if not impossible, to measure [ 33 ].…”

Shifting cultivation and hunting across the savanna-forest mosaic in the Gran Sabana, Venezuela: facing changes

“…Large scale analysis of hunting rates might overlook the factors operating locally, such as landscape type and matrix, wildlife diversity, cultural hunting taboos, religion, type of protein sources (fishing, hunting), hunting technology, economic context or emerging threats, leading to misinterpretations and incorrect management decisions. Understanding the relationship between human activities and wildlife diversity patterns is crucial to identify the most appropriate conservation interventions in complex landscapes with high biological and cultural diversity (Weinbaum et al, 2013;Gavin et al, 2015;Rovero et al, 2020).…”