Unraveling the scales of effect of landscape structure on primate species richness and density of titi monkeys (Callicebus nigrifrons)

In the Anthropocene, many animal populations are increasingly confined to human‐modified landscapes, in which different spatial variables describing landscape composition and configuration influence species persistence. Forest specialist species are particularly vulnerable to these landscape disturbances. Yet, landscape effects may be undetected if assessed at the wrong spatial scale. Thus, identifying the “scale of effect”, which is the optimal spatial scale for estimating ecological responses to each landscape variable, is needed to understand the impact of landscape structure modification on species. Here, we explored the scale of effect of two compositional (forest cover and anthropogenic cover) and two configurational landscape variables (forest patch density and forest edge density) on two ecological responses: primate species richness and group densities of titi monkeys (Callicebus nigrifrons). We sampled 16 study sites in northeastern São Paulo State, Brazil. For each site, we measured each landscape variable within 10 different‐sized landscapes ranging from 0.2 to 28.3 km2 to identify the scale of effect of each landscape variable. The strength of all the primate‐landscape relationships varied across spatial scales. Although both ecological responses were most strongly associated with forest cover at the largest scale, the scale of effect of the other landscape variables differed between the response variables. These results suggest that each response variable is shaped by landscape patterns and processes operating across different spatial scales. We highlight the importance of separately assessing the scale of effect of each landscape variable on each ecological response to better understand the impact of landscape structure on species persistence341150159CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP312045/2013‐1; 312292/2016‐388881.068425/2014‐02012/14245‐2; 2013/50421‐2The authors are grateful to the landowners for granting permission to collect data on their properties. The authors would like to thank the Empresa Brasileira de Pesquisa Agropecuária and the Forest Institute of the State of São Paulo Environment Department for permission to conduct our research in forest patches from Embrapa Agropecuária Sudeste and in Parque Estadual de Vassununga, respectively. The authors would also like to thank the Zoos of the municipalities of Bauru and Piracicaba for the opportunity to test the recordings with captive animals, and the Forest Institute of the State of São Paulo Environment Department and Duratex Lençóis Paulista for permission to conduct these tests with wild animals in the forest remnants of Jataí Ecological Station and Reserva Natural Olavo Setúbal, respectively. This research was funded by São Paulo Research Foundation (FAPESP, process 2012/14245‐2). We also received field equipment from Idea Wild. M.C.R. thanks to CNPq (Brazilian Government Research Council) for research grants (312045/2013‐1 and 312292/2016‐3), to FAPESP (process 2013/50421‐2) and CAPES (Procad project # 88881.068425/2014‐0) for their financial support. The authors would finally thank B.H. Saranholi for comments on earlier versions of this manuscript, C.B. Caselli for suggestions on statistical analyses, and S. Hongo and an anonymous reviewer for their constructive suggestions that contributed to improve the manuscrip