Feeding ecology and postural behaviour of the three-toed sloth (Bradypus variegatus flaccidus) in northern Venezuela

Abstract

We studied the diet, activity budget, vertical ranging, and postural behaviour in relation to weather of the three-toed sloth (Bradypus variegatus flaccidus) in disturbed montane forest remnants (1150 m asl) in northern Venezuela. Sloths spent most (72.9%) of their time resting and had a nearly exclusive (99.4%) leaf diet. While resting they assumed a sitting -not hanging -posture mostly (90.2% of observations). Species of three families, Clethraceae, Cecropiaceae, and Clusiaceae accounted for 77% of feeding records. Young leaves (67.2%) accounted for most of the leaf diet. Activity and posture were dependent on weather conditions. Sloths fed more often during mid-day hours and tended to rest more at dawn and dusk. In northern Venezuela sloths tended to use more frequently the upper strata of the canopy, while in warmer lowland sites they use intermediate levels more often. They adopted postures that maximized exposure of ventral surfaces to incident solar radiation when sunny, but minimized their surface area by huddling when cloudy, foggy or rainy. We propose that sunning behaviour of sloths may speed up their fermentation rate, and ultimately, might have been an important selective factor in the evolution of derived upside-down posture of sloths.

Towards a standard framework to describe behaviours in the common-sloth (Bradypus variegatus Schinz, 1825): novel interactions data observed in distinct fragments of the Atlantic forest, Brazil

“…Our updated framework (Urbani and Bosque, 2006; plus our proposed categories) will be a useful tool in the standardise description of common sloth behaviour in natural environments. It enables the comparison between different studies, both qualitatively (it assures that exactly the same posture and locomotion events are being named when different people are observing the common-sloth individuals), as quantitatively (allows the correct behavioural categories' frequency comparison).…”

“…An animal was considered to be the same individual in different days of field work if it was found in the same tree or at least in the adjacent ones and no ambiguity was detected (Urbani and Bosque, 2006). Also, every time a common sloth was found we did a simple record of their posture and behaviour, according to Urbani and Bosque (2006).…”

“…Also, every time a common sloth was found we did a simple record of their posture and behaviour, according to Urbani and Bosque (2006). Few studies had made an exhaustive description of common sloth behaviours (Consentino, 2004;Queiroz, 1995;Urbani and Bosque, 2006). Thus we have chosen to follow Urbani and Bosque (2006) description because the authors based their categories both in their own field experience and in previous works.…”

“…Ballesteros et al, 2009;Consentino, 2004;Mendel, 1985;Queiroz, 1995;Urbani and Bosque, 2006;Vaughan et al, 2007). So, as stated in the Methodology section, we have chosen a list of behaviour categories that had considered previous behaviour description on common sloth (Urbani and Bosque, 2006). Yet, in our opinion, Urbani and Bosque`s (2006) categorization was not able to fully describe the common sloth behaviours.…”

“…Life in the trees' canopy, their slow and silent movements, together with a camouflaged pelage makes sloths extremely difficult to be observed in nature. Consequently, although the common sloth's widespread distribution (Moraes-Barros et al, 2010), few ecological studies were made so far (Ballesteros et al, 2009;Consentino, 2004;Queiroz, 1995;Soares and Carneiro, 2002;Urbani and Bosque, 2006;Vaughan et al, 2007), and basic ethological data are barely understood. For instance, reproductive means were only reported once (Bezerra et al, 2008), more descriptive parental care three times (Bezerra et al, 2008;Soares and Carneiro, 2002;Pinheiro, 2008), and territorial occupancy is unclear (Bezerra et al, 2008;Hayssen, 2010;Lara-Ruiz and Srbeck-Araujo, 2006).…”