Community structure and diversity of tropical forest mammals: data from a global camera trap network

Abstract

Terrestrial mammals are a key component of tropical forest communities as indicators of ecosystem health and providers of important ecosystem services. However, there is little quantitative information about how they change with local, regional and global threats. In this paper, the first standardized pantropical forest terrestrial mammal community study, we examine several aspects of terrestrial mammal species and community diversity (species richness, species diversity, evenness, dominance, functional diversity and community structure) at seven sites around the globe using a single standardized camera trapping methodology approach. The sites-located in Uganda, Tanzania, Indonesia, Lao PDR, Suriname, Brazil and Costa Rica-are surrounded by different landscape configurations, from continuous forests to highly fragmented forests. We obtained more than 51 000 images and detected 105 species of mammals with a total sampling effort of 12 687 camera trap days. We find that mammal communities from highly fragmented sites have lower species richness, species diversity, functional diversity and higher dominance when compared with sites in partially fragmented and continuous forest. We emphasize the importance of standardized camera trapping approaches for obtaining baselines for monitoring forest mammal communities so as to adequately understand the effect of global, regional and local threats and appropriately inform conservation actions.

Influence of camera-trap sampling design on mammal species capture rates and community structures in southeastern Brazil

“…However, there was a lack of significant correlation between climatic variables and capture success for most of the species recorded in the present study (see Methods for details), and the inter-annual variation in rainfall may have not contributed significantly to the variation in the capture rate among the years. Although camera traps are well suited to standardization when compared to other sampling methods for mammals (Ahumada et al 2011), the places where the data are collected influences the efficiency in obtaining adequate measurements of species studied Engeman (2005), and the choices about where and when the camera traps will be placed can influence the sampling process. These choices can lead to biased results because species use the environment differently and researchers use different criteria to define the best sampling locations (Larrucea et al 2007).…”

“…If these tasks cannot be accomplished, we suggest that camera-trapping rates should be best used as inputs for presence and detection analyses and for behavior inferences (regarding the preferential use of habitats and activity patterns, for example). Alternatively, the camera-trap data from appropriate sampling designs could be used to estimate species occupancy, which may be used as a surrogate for abundance , MacKenzie & Royle 2005, as applied by Ahumada et al (2011). When it is possible to distinguish individuals, camera-trap data can be used to estimate population parameters through the use of capture-recapture probabilistic models, as proposed by Karanth (1995) and Karanth & Nichols (1998).…”

“…These devices have been widely used in mammal inventories and are especially effective for detecting elusive, cryptic and/or rare species (e.g., Srbek-Araujo & Chiarello 2005, Tobler et al 2008, Ahumada et al 2011, Espartosa et al 2011. In addition to this usual application, Carbone et al (2001) consider that the use of indices to estimate the relative abundance of mammals would increase the use of this tool because only a small fraction of the species may have the individuals identified and studied using capture-recapture methods based on camera traps.…”

Detecting diversity: emerging methods to estimate species diversity

“…One option is to use a 'predict first, assemble later' approach [28] to estimate species richness, where species are modeled individually and richness measures are calculated through aggregation with established metrics [29,30]. Although this approach allows occupancy to be modeled with species-specific covariates, modeling species individually restricts inferences about diversity to species that have been detected multiple times, which excludes species that are rare or are undetected across all sites (Figure 2).…”

Mobility explains the response of aerial insectivorous bats to anthropogenic habitat change in the Neotropics

“…Type and intensity of land degradation has an effect on habitat quality and structure, which in turn impacts species populations, often in a negative way. At highly altered sites, tropical mammal communities are characterized by decreased species richness and diversity as well as by higher dominance compared to less disturbed habitats (Ahumada et al, 2011). Urbanization affects community composition drastically Sattler et al, 2010;Threlfall et al, 2011) and may lead to homogenization of urban species assemblages worldwide (McKinney, 2006).…”