The role of environmental temperature on movement patterns of giant anteaters

Abstract

Mammals can show conspicuous behavioral responses to thermal variation, including changes in movement patterns. We used an integrative approach to understand how environmental temperature can drive the movement behavior of a mammal with low capacity for physiological thermoregulation, the giant anteater (Myrmecophaga tridactyla). We tracked 52 giant anteaters in 7 areas throughout the Brazilian savannah. We estimated the distance moved, area used, use of forest areas, and mean environmental temperature for each monitoring day of each individual. We modeled these data with Mixed Structural Equations — considering the possible interactions between our variables and controlling for sex and body mass. Giant anteaters reduced displacement and increased forest use with decreasing environmental temperature, probably because of their low body heat production. It is possible that they reduce distance moved and area used by reducing the duration of activity. With decreasing temperature, forest habitats become warmer than open ones, besides buffer rain and chilly winds. Reducing displacement and using forests are important strategies to reduce body heat loss and the energetic costs of thermoregulation. However, decreasing movement can limit food access and, consequently, fitness. Therefore, we highlight the importance of forests as thermal shelters. With increasing frequency and intensity of extreme weather events, we showed the need to preserve forest patches to offer suitable conditions for tropical mammals’ behavioral thermoregulation. In this context, policies favoring deforestation on Brazilian territory are especially worrisome. Finally, we emphasize the need of integrative approaches to understand the complex interactions between organisms and the environment.

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

“…We highlight the need to consider the sexual differences on movement strategies and the role of forests as an important thermal resource driving giant anteaters’ spatial requirements (also see [ 96 ]). In accordance with [ 36 ], we strongly suggest that management efforts should focus on maintaining the giant anteaters’ access to forest patches inside their home ranges to provide environmental conditions for behavioral thermoregulation. Both intrinsic and environmental traits driving animal movement should be integrated when establishing conservation strategies for populations and species.…”

“…Decreasing the proportion of forest inside giant anteaters' home range led males and females to an increase in the home range size. This is probably because giant anteaters present a low capacity for physiological thermoregulation [37], and less forest implies less access to thermal shelters and, consequently, a reduced habitat thermal quality [34][35][36]. As a result, animals would increase the home range size as a strategy to maximize the chances of accessing this thermal resource.…”

“…In this scenario, their low reproductive rate and long periods of parental care make giant anteaters conservation status even more worrisome [ 31 , 32 ]. Despite being commonly associated with open habitats [ 33 ], forests have a fundamental role in giant anteater thermoregulation [ 34 – 36 ]. This is because giant anteaters present reduced body heat production [ 37 ] and low capacity of physiological thermoregulation, and forests act as important thermal shelters.…”

“…Despite the efforts to understand giant anteaters’ movement ecology, previous estimates of their home range size have ignored the intrinsic autocorrelation of high-resolution movement data and have not been based on movement models, probably generating underestimated results [ 24 , 30 ]. While some studies showed no evidence of sexual effects on their movement [ 36 , 40 ], other ones showed males presenting longer daily activity time [ 41 , 42 ] and using larger areas than females [ 42 ]. Because of their sexual size dimorphism [ 36 ], the possible influence of body mass on movement needs to be considered when assessing sexual effects.…”

“…While some studies showed no evidence of sexual effects on their movement [ 36 , 40 ], other ones showed males presenting longer daily activity time [ 41 , 42 ] and using larger areas than females [ 42 ]. Because of their sexual size dimorphism [ 36 ], the possible influence of body mass on movement needs to be considered when assessing sexual effects. Besides, although we know that giant anteaters select forests to set their home ranges and allocate time within it [ 42 ], we still ignore if the proportion of forest cover within home ranges influences their movement patterns and spatial requirements.…”