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

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.

Large Protected Areas Safeguard Mammalian Functional Diversity in Human-Modified Landscapes

“…For the insectivores recorded (armadillos and anteaters), invertebrates (especially ants and termites) are their main food resource [109][110][111][112], which can be unpredictably distributed in the landscape or become scarce in certain seasons of the year [113,114]. In addition, the anteaters and armadillos are known for their low thermoregulation capacity and use forest areas as thermal shelters [112,115,116], so bearing in mind that the studied patches are mainly composed of forests, it is likely that larger patches with better opportunities for thermal regulation might favor insectivores presence.…”

The socio-spatial ecology of giant anteaters in the Brazilian Cerrado

“…Existing knowledge on giant anteater sociality is based on brief reports and are primarily from observations on captive animals (del Valle Jerez & Halloy, 2003; Bertassoni & Milléo Costa, 2010; Eyer & Miller, 2020), with only limited data on the behaviour of free-ranging animals (Montgomery & Lubin, 1975; Shaw et al ., 1987; Bertassoni & Milléo Costa, 2010; Bertassoni et al ., 2021; Giroux et al ., 2021). From these, giant anteaters are described as mostly solitary in the wild except during the mating season where courtship behaviour has been observed (Shaw et al ., 1987; Braga et al ., 2010; Bertassoni & Desbiez, 2022).…”

Safeguarding sloths and anteaters in the future: Priority areas for conservation under climate change

“…The growing spatial gap in the species richness' pattern found for the future projected distribution illustrates the already known impact of climate change in South America: the replacement of the tropical forest by savannas (Anadón et al, 2014; Salazar et al, 2007). Most of the Pilosa species are exclusively arboreal or scansorial, thus dependent on forest cover as their primary habit (Montgomery, 1985) and dependent on ambient temperature for thermoregulation purposes (Giroux et al, 2021). For instance, the local occurrence of B. torquatus decreases abruptly when forest cover is below 35% (Santos, Bailey, et al, 2019) and although M. tridactyla uses open areas to forage, it still depends on covered vegetation areas as thermic refuges (Bertassoni et al, 2017).…”

“…Nonetheless, even though most extant species are not officially threatened with extinction, the high number of extinctions in the past indicates this group to be greatly vulnerable to the ongoing climate change, which in synergy with other anthropogenic impacts can compromise ecosystem functioning and the structure of communities, ultimately leading to species extinction (Brook et al, 2008; Montgomery & Sunquist, 1975). Distinctively, Xenarthrans have a low basal metabolic rate and, consequently, have lower body temperature compared to other mammals with a similar body mass, thus, they maintain their body temperature in response to the ambient temperature (Giroux et al, 2021; McNab, 1985). This means drastic external temperature changes would also provoke changes to Xenarthran's body temperature, increasing their vulnerability to climate change.…”