Habitat heterogeneity as a local and regional-scale driver of primate assemblage structure in northernmost Brazilian Amazonia

Abstract

We performed line transect surveys in two fishbone human settlements (defined as clearings cut through forests in a fishbone pattern, extending along secondary roads from a main road) in different vegetation types, as well as in one protected area. A total of 410 sightings of eight primate species were recorded in the three study areas. The mean total primate abundance was 3.28 groups/10 km walked, and there were significant differences between areas with different plant physiognomies. The abundance of the larger primate speciesAlouatta macconnelliandAteles paniscus(Atelidae) was higher in the dense ombrophilous forests of the Entre Rios human settlement, whereas those of all the other species were higher in the forest mosaics of the Novo Paraíso human settlement and Viruá National Park. The habitat generalistSapajus apellapresented the highest abundances in all the areas. No significant differences were detected in relative biomass between study areas. Additionally, no significant differences were detected in the overall abundances or relative biomasses of the hunted species (Sapajus apella,Alouatta macconnelli,Ateles paniscus, andChiropotes chiropotes) between study areas. Human impact has been recognized as shaping primate assemblages. However, in this study, primates were not part of the dietary repertoire of the non-Amazonian immigrants inhabiting the fishbone human settlements. Thus, although the primate assemblages varied considerably at the regional and local level, they were shaped by habitat heterogeneity, which allowed the competing species to coexist through habitat segregation.

Tree reproductive phenology determines the abundance of medium–sized and large mammalian assemblages in the Guyana shield of the Brazilian Amazonia

“…Covariates of forest structure and productivity, such as stratification, floristic diversity, and phenology have been proposed as determinants of mammalian abundance (Malcolm, 1995;Gentile and Fernandez, 1999;Grelle, 2003;Marshall et al, 2014;Luna et al, 2017). Gadelha et al (2017), studying a primate community in a habitat similar to that in the current study, found a significant association between mammalian abundance, and absolute dominance of trees, number of clearings, and vegetation height. No studies to date, however, had tested the effects of the forest structure and productivity covariates on whole assemblages of medium-and large-sized mammals in totally protected areas in the Brazilian Amazonia.…”

“…It has been shown in our previous studies (Gadelha et al, 2017;Luna et al, 2017) that at the regional scale (Peterson et al, 2011), the abundance of the mammalian assemblages can be determined by the physical structure of forests, whether it be in highly-heterogeneous vegetation mosaics, such as in the northern part of the Guyana Shield, or the ombrophilous forests of the southern part, or a transition between them. Now, we have also shown that at the local scale (Peterson et al, 2011), forest structure and productivity, and more specifically food availability and its fluctuations, determined the abundance of the mammalian assemblages.…”