Estimating Species Richness and Modelling Habitat Preferences of Tropical Forest Mammals from Camera Trap Data

Abstract

Medium-to-large mammals within tropical forests represent a rich and functionally diversified component of this biome; however, they continue to be threatened by hunting and habitat loss. Assessing these communities implies studying species’ richness and composition, and determining a state variable of species abundance in order to infer changes in species distribution and habitat associations. The Tropical Ecology, Assessment and Monitoring (TEAM) network fills a chronic gap in standardized data collection by implementing a systematic monitoring framework of biodiversity, including mammal communities, across several sites. In this study, we used TEAM camera trap data collected in the Udzungwa Mountains of Tanzania, an area of exceptional importance for mammal diversity, to propose an example of a baseline assessment of species’ occupancy. We used 60 camera trap locations and cumulated 1,818 camera days in 2009. Sampling yielded 10,647 images of 26 species of mammals. We estimated that a minimum of 32 species are in fact present, matching available knowledge from other sources. Estimated species richness at camera sites did not vary with a suite of habitat covariates derived from remote sensing, however the detection probability varied with functional guilds, with herbivores being more detectable than other guilds. Species-specific occupancy modelling revealed novel ecological knowledge for the 11 most detected species, highlighting patterns such as ‘montane forest dwellers’, e.g. the endemic Sanje mangabey (Cercocebus sanjei), and ‘lowland forest dwellers’, e.g. suni antelope (Neotragus moschatus). Our results show that the analysis of camera trap data with account for imperfect detection can provide a solid ecological assessment of mammal communities that can be systematically replicated across sites.

Biodiversity estimates from different camera trap surveys: a case study from Osogovo Mt., Bulgaria

“…Many studies point out the importance of camera trapping for inventorying the community of medium to large terrestrial mammals (Silveira et al, 2003;O'Connell et al, 2011;Rovero et al, 2014), even for the discovery of new mammal species (Rovero et al, 2008). During one of the analysed studies (Study 3) on Osogovo Mt.…”

“…Globally, a limited number of publications address the way mammal registrations accumulate over time (Kauffman et al, 2007;Tobler et al, 2008;Rovero et al, 2010Rovero et al, , 2014Bischof et al, 2014;Si et al, 2014;Kolowski & Forrester, 2017), which are based mainly on tropical species. Furthermore, studies utilise various camera trap models and schemes positioning in the field such as random points, locations based on expert opinion or local knowledge or specifically designed grids (O'Brien, 2008) which is often not further discussed when assessing the results.…”

Medium and large mammal richness from the marine and coastal wildlife refuge of Pacoche, Ecuador

“…Las trampas cámara proveen una forma alternativa y fácil de estandarizar y de replicar para estudiar mamíferos medianos y grandes (Tobler et al 2008). Varios factores han llevado al incremento de estudios con trampas cámara en la última década, entre los cuales se incluye la posibilidad de minimizar el error de detección, en especial para algunas especies crípticas y difíciles de observar, la disminución en su costo y la posibilidad de estandarizar y replicar el mismo muestreo a diferentes lugares (Tobler et al 2008;Ahumada et al 2011;Ahumada et al 2013;Rovero et al 2014). En Ecuador se han realizado algunos estudios usando esta metodología pero han estados enfocados en la diversidad de grupos específicos como los carnívoros (Hodge y Arbogast 2015) o algunos aspectos de la biología de una especie en particular (Blake et al 2010).…”

Daily activity patterns of large and medium-sized mammals based on camera traps data in the Central Forest Nature Reserve, Valdai Upland, Russia

“…The unloading, storage, sorting and initial processing of images were carried out with the help of Reconyx software -MapView Professional v.3.4 (Reconyx, Inc.). The main performance indicators for camera traps are standard for this kind of research (Mohd-Azlan & Sharma, 2006;Kelly & Holub, 2008;Rovero et al, 2014). These include the number of trap nights (or camera days) spent by one camera at i-th location (TN); number of animal passes/registrations (TE -trap events) at i-th location; total number of pictures/frames for each species; the relative abundance index (RAI or TS -trap success), which was calculated by formula:…”