Feeding ecology and postural behaviour of the three-toed sloth (Bradypus variegatus flaccidus) in northern Venezuela
Urbani, B. and Bosque, C., 2007. Feeding ecology and postural behaviour of the three-toed sloth (Bradypus variegatus flaccidus) in northern Venezuela. Mammalian Biology-Zeitschrift für Säugetierkunde, 72(6), pp.321-329.
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.
Key words: Bradypus, ecology, biology, physiology, metabolism, temperature, diet