Forest maturity has a stronger influence on the prevalence of spider monkeys than howler monkeys in an anthropogenically impacted rainforest landscape

Abstract

The transformation and depletion of primary forest over the past few decades have placed almost half of the world’s primate species under the threat of extinction. Developing any successful conservation program for primates requires distribution and demography data, as well as an understanding of the relationships between these factors and their habitat. Between March and June 2010 and 2011 we collected data on the presence and demographic parameters of howler and spider monkeys by carrying out surveys, and validated our findings using local knowledge. We then examined the relationship between forest type and the presence of these primates at 54 sites in the northern area of the Selva Zoque Corridor, Mexico. We detected 86 spider monkey groups across 31 plots and censused 391 individuals (mean ± SD = 5.9 ± 3.0 individuals per sub-group, n = 67 sub-groups). We also detected 69 howler monkey groups across 30 plots and censused 117 individuals (mean ± SD = 5.3 ± 2.4 individuals per group, n = 22 groups). Howler monkey presence was not related to any specific vegetation type, while spider monkeys were present in areas with a higher percentage of tall forest (trees > 25 m high). Overall, spider monkeys were more prevalent than howler monkeys in our sampling sites and showed demographic characteristics similar to those in better protected areas, suggesting that the landscape features in the Uxpanapa Valley are suitable for their needs. Conversely, howler monkey presence was found to be more limited than in other regions, possibly due to the extended presence of spider monkeys.

Drivers of jaguar (Panthera onca) and puma (Puma concolor) predation on endangered primates within a transformed landscape in southern Mexico

“…There are several possible reasons for lower predation on howler monkeys than spider monkeys. First, the overall prevalence of howler monkeys appears to be lower than that of spider monkeys in the region (Shedden et al, 2022), and large cats tend to use prey in accordance with their abundance (Hayward et al, 2016). This abundance‐based difference is supported by our finding that howler monkey consumption was higher in sites with more howler monkey groups.…”

“…Primate surveys were performed in parallel and within the same areas as large cat scat collection, as part of a larger project studying biodiversity in the region (Shedden et al, 2022). Two species of primates were found in our study site: the Mexican mantled howler monkey ( Alouatta palliata mexicana ) and the spider monkey ( Ateles geoffroyi ), both classified as Endangered in the IUCN Red List (Cuarón et al, 2020; Rosales‐Meda et al, 2020).…”

“…Two species of primates were found in our study site: the Mexican mantled howler monkey ( Alouatta palliata mexicana ) and the spider monkey ( Ateles geoffroyi ), both classified as Endangered in the IUCN Red List (Cuarón et al, 2020; Rosales‐Meda et al, 2020). The data on primate occurrences and number of groups used for our analysis were derived from these surveys (Shedden et al, 2022).…”

“…Our work aims to contribute toward a better understanding of jaguar and puma diet in an anthropogenically altered landscape, as well as to help assess the implications of large cat predation for primate conservation. In particular, information on large cat predation would provide necessary data to develop primate conservation strategies for our study site, since both spider ( Ateles geoffroyi ) and howler ( Alouatta palliata mexicana ) monkeys are classified as endangered (IUCN, 2023) and face increasing threat due to habitat transformation in the area (Galán‐Acedo et al, 2018; Shedden et al, 2022).…”