Factors influencing terrestriality in primates of the Americas and Madagascar
Authors: Eppley Timothy M. , Hoeks Selwyn , Chapman Colin A. , Ganzhorn Jörg U. , Hall Katie , Owen Megan A. , Adams Dara B. , Allgas Néstor , Amato Katherine R. , Andriamahaihavana McAntonin , Aristizabal John F. , Baden Andrea L. , Balestri Michela , Barnett Adrian A. , Bicca-Marques Júlio César , Bowler Mark , Boyle Sarah A. , Brown Meredith , Caillaud Damien , Calegaro-Marques Cláudia , Campbell Christina J. , Campera Marco , Campos Fernando A. , Cardoso Tatiane S. , Carretero-Pinzón Xyomara , Champion Jane , Chaves Óscar M. , Chen-Kraus Chloe , Colquhoun Ian C. , Dean Brittany , Dubrueil Colin , Ellis Kelsey M. , Erhart Elizabeth M. , Evans Kayley J. E. , Fedigan Linda M. , Felton Annika M. , Ferreira Renata G. , Fichtel Claudia , Fonseca Manuel L. , Fontes Isadora P. , Fortes Vanessa B. , Fumian Ivanyr , Gibson Dean , Guzzo Guilherme B. , Hartwell Kayla S. , Heymann Eckhard W. , Hilário Renato R. , Holmes Sheila M. , Irwin Mitchell T. , Johnson Steig E. , Kappeler Peter M. , Kelley Elizabeth A. , King Tony , Knogge Christoph , Koch Flávia , Kowalewski Martin M. , Lange Liselot R. , Lauterbur M. Elise , Louis Edward E. , Lutz Meredith C. , Martínez Jesús , Melin Amanda D. , de Melo Fabiano R. , Mihaminekena Tsimisento H. , Mogilewsky Monica S. , Moreira Leandro S. , Moura Letícia A. , Muhle Carina B. , Nagy-Reis Mariana B. , Norconk Marilyn A. , Notman Hugh , O’Mara M. Teague , Ostner Julia , Patel Erik R. , Pavelka Mary S. M. , Pinacho-Guendulain Braulio , Porter Leila M. , Pozo-Montuy Gilberto , Raboy Becky E. , Rahalinarivo Vololonirina , Raharinoro Njaratiana A. , Rakotomalala Zafimahery , Ramos-Fernández Gabriel , Rasamisoa Delaïd C. , Ratsimbazafy Jonah , Ravaloharimanitra Maholy , Razafindramanana Josia , Razanaparany Tojotanjona P. , Righini Nicoletta , Robson Nicola M. , Gonçalves Jonas da Rosa , Sanamo Justin , Santacruz Nicole , Sato Hiroki , Sauther Michelle L. , Scarry Clara J. , Serio-Silva Juan Carlos , Shanee Sam , Lins Poliana G. A. de Souza , Smith Andrew C. , Smith Aguilar Sandra E. , Souza-Alves João Pedro , Stavis Vanessa Katherinne , Steffens Kim J. E. , Stone Anita I. , Strier Karen B. , Suarez Scott A. , Talebi Maurício , Tecot Stacey R. , Tujague M. Paula , Valenta Kim , Van Belle Sarie , Vasey Natalie , Wallace Robert B. , Welch Gilroy , Wright Patricia C. , Donati Giuseppe , Santini Luca 
Published: October 2022

Among mammals, the order Primates is exceptional in having a high taxonomic richness in which the taxa are arboreal, semiterrestrial, or terrestrial. Although habitual terrestriality is pervasive among the apes and African and Asian monkeys (catarrhines), it is largely absent among monkeys of the Americas (platyrrhines), as well as galagos, lemurs, and lorises (strepsirrhines), which are mostly arboreal. Numerous ecological drivers and species-specific factors are suggested to set the conditions for an evolutionary shift from arboreality to terrestriality, and current environmental conditions may provide analogous scenarios to those transitional periods. Therefore, we investigated predominantly arboreal, diurnal primate genera from the Americas and Madagascar that lack fully terrestrial taxa, to determine whether ecological drivers (habitat canopy cover, predation risk, maximum temperature, precipitation, primate species richness, human population density, and distance to roads) or species-specific traits (body mass, group size, and degree of frugivory) associate with increased terrestriality. We collated 150,961 observation hours across 2,227 months from 47 species at 20 sites in Madagascar and 48 sites in the Americas. Multiple factors were associated with ground use in these otherwise arboreal species, including increased temperature, a decrease in canopy cover, a dietary shift away from frugivory, and larger group size. These factors mostly explain intraspecific differences in terrestriality. As humanity modifies habitats and causes climate change, our results suggest that species already inhabiting hot, sparsely canopied sites, and exhibiting more generalized diets, are more likely to shift toward greater ground use.