Sexual, allometric and forest cover effects on giant anteaters' movement ecology.

Aline Giroux,Zaida Ortega,Arnaud Léonard Jean Desbiez,Luiz Gustavo Rodrigues Oliveira-Santos,Alessandra Bertassoni,Nina Attias,Bi-Song Yue

doi:10.1371/journal.pone.0253345

Abstract

Knowing the influence of intrinsic and environmental traits on animals’ movement is a central interest of ecology and can aid to enhance management decisions. The giant anteater (Myrmecophaga tridactyla) is a vulnerable mammal that presents low capacity for physiological thermoregulation and uses forests as thermal shelters. Here, we aim to provide reliable estimates of giant anteaters’ movement patterns and home range size, as well as untangle the role of intrinsic and environmental drivers on their movement. We GPS-tracked 19 giant anteaters in Brazilian savannah. We used a continuous-time movement model to estimate their movement patterns (described by home range crossing time, daily distance moved and directionality), and provide an autocorrelated kernel density estimate of home range size. Then, we used mixed structural equations to integratively model the effects of sex, body mass and proportion of forest cover on movement patterns and home range size, considering the complex net of interactions between these variables. Male giant anteaters presented more intensive space use and larger home range than females with similar body mass, as it is expected in polygynous social mating systems. Males and females increased home range size with increasing body mass, but the allometric scaling of intensity of space use was negative for males and positive for females, indicating different strategies in search for resources. With decreasing proportion of forest cover inside their home ranges, and, consequently, decreasing thermal quality of their habitat, giant anteaters increased home range size, possibly to maximize the chances of accessing thermal shelters. As frequency and intensity of extreme weather events and deforestation are increasing, effective management efforts need to consider the role of forests as an important thermal resource driving spatial requirements of this species. We highlight that both intrinsic and environmental drivers of animal movement should be integrated to better guide management strategies.

Highlights

Animal movement is a key process of ecology, driving animals’ survival and fitness [1]
Once home range crossing time indicates the timescale of autocorrelation in position, our results show that, on average, a twodays interval between consecutive relocations is necessary to consider them spatially independent [63]
The use of mixed-SEM allowed us to disentangle the effects of sex, body mass and proportion of forest on movement patterns and home range size, simultaneously estimating the direction and intensity of direct and indirect effects

Summary

Introduction

Animal movement is a key process of ecology, driving animals’ survival and fitness [1]. Describing movement patterns and quantifying the home range size allow us to better understand the ecology and spatial requirements of animals to make appropriate management decisions that can help to preserve wildlife populations [5, 6]. Such knowledge has become even more important as human actions are increasingly endangering natural systems [7, 8]. Theoretical and empirical studies have more often focused on understanding ‘typical’ movement of a species than understanding its variation [9] Both movement patterns and home range size widely vary between individuals within a population, and these variations are commonly influenced by intrinsic and environmental traits [5, 7]

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Conclusion