Sloths in the city: Unexpectedly high density of pale-throated three-toed sloths (Bradypus tridactylus) found in an urban forest patch in Paramaribo, Suriname

Background/Question/Methods

Much remains to be learned of the natural history of the pale-throated three-toed sloth, Bradypus tridactylus. Because they are generally stationary, freeze in response to loud sounds, avoid predators by mov­ing slowly, and are extremely silent when mak­ing rare and careful movements, this species is difficult to locate—even when gregarious in anthropogenic habitats. Consequently, studies of the ecology, abun­dance, and density of B. tridactylus are lacking. Rescue operations provide a unique opportunity to inventory, sample, and study species that are otherwise difficult to observe and capture. A rescue effort by the Green Heritage Fund Suriname of arboreal mammals displaced during deforestation of a 6.8 ha plot in northwest Paramaribo, Suriname allowed for the collection and assessment of demographic and physical attributes, including gender, body mass, length, and other features, of an entire B. tridactylus population in an urban, con­tiguous, relatively undisturbed, and isolated forest patch.

Results/Conclusions

Rescued or observed animals included 137 pale-throated three-toed sloths (Bradypus tridactylus), eight two-toed sloths (Choloepus didactylus), three Brazilian porcupines (Coendou prehensilis), and three silky anteaters (Cyclopes didactylus). Two lesser anteaters (Tamandua tetradactyla) – a mother and baby – were seen but not rescued. Due to their inability to escape, it is likely that almost all of the pale-throated sloths in the forested plot were captured during the thirty-days of clear-cutting. Comprising 91% of the total rescued animals, the 137 B. tridactylus included 61 males, 56 females, 15 juveniles, and five adults that could not be sexed. Data reveal a population of reasonably healthy but smaller animals at a population density of 20.1 animals/ha far exceeding any previous reports for this species. While a number of urbanization processes may have the potential to explain this high density, this density, orders of magnitude higher than previously reported, suggests that sloths may be an interesting and important component of tropical urban landscapes. Indeed, reports of high densities of other species of sloths in other urban areas suggests that, this group should be considered urbanophilic, affirming the need to recognize that the establishment of green spaces in tropical cities is likely to encourage their conservation.