SLOTHS
Pygmy sloth
Bradypus pygmaeus
RANGE

The pygmy sloth is known only from Isla Escudo de Veraguas, in the islands of Bocas del Toro, Panama. Sloths on the younger islands of the Bocas del Toro archipelago are conspecific with Bradypus variegatus. Isla Escudo de Veraguas has an area of approximately 4.3 km2 and is about 17.6 km from the mainland of Panama.


DESCRIPTION

This is the smallest of all sloths; adults weigh no more than 3 kg. It has dark gray fur that is darker (and longer) on the shoulder, and agouti gray-brown on the throat. There is a dark midsagittal stripe on the blotchy-colored dorsum. Its tan face bears a dark band across the brow and some orange coloring around the eyes. Longer hair on the crown forms a hood around the short facial hair. Adult males have a black and orange spot (called speculum) between the shoulder blades. The forelimbs bear three digits with large claws and are longer than the hindlegs, which also have three digits. The tail is very short and stumplike.

HABITAT

This smallest of all sloths is found both in mangrove patches and on the interior of Isla Escudo. Although previously thought to exclusively inhabit the red mangroves of the island, recent tracking studies have found the sloths on the interior of the island, in dense tropical rainforest. Because of the difficulty of censusing cryptic canopy mammals, their density and abundance in the thicker forests is unknown.

BIOLOGY

There is no information available on the population status of B. pygmaeus. Previous censuses only searched for sloths in mangroves, which comprise less than 3% of the island. For instance, a total of 79 individuals were observed during the most recent census, 70 of which were in the mangroves and nine in non-mangrove trees in the periphery of the mangroves (Kaviar et al. 2012). However, censusing cryptic, slow moving arboreal mammals in dense forest is challenging and limited. No estimates on the total island population have been made; the population is likely to be relatively small. In the mangroves the population density of this sloth is relatively high (5.8 sloths/ha).
Nothing is known about their reproduction, lifespan, home range, or diet, although it is suspected that it primarily, if not exclusively, feeds on mangrove leaves. Its population is likely larger than previously estimated, but is still limited due to its restricted habitat range. The population trend is decreasing.

THREATS

Although it was previously thought that locals would eat pygmy sloths, this was recently disproven.
Although the island is uninhabited, there are seasonal visitors (fishermen, campesinos, lobster divers, tourists, and local people) who harvest timber to maintain wooden houses on the island. Preliminary studies suggest a reduced level of genetic diversity for pygmy sloths compared to its putative population of origin, the common sloth population from mainland Panama. This is expected, considering the history of species diversification and isolation on the island. However, signs of a more recent population bottleneck were also detected (Silva et al. 2010, N. Moraes-Barros pers. comm. 2013). These results highlight the need of a continuous evaluation of the population status, trends, and additional studies considering a possible scenario of endogamic depression if the (already low) population size decreases any further.
Despite having been designated as a protected landscape through a governmental resolution in 2009, a number of domestic and international efforts have been mounted to develop tourism infrastructure on the island. This includes plans for an eco-lodge, a casino, a marina, and a banking centre. The current status of the island’s custody is vague; a governmental resolution, and thus the protected status of the island, cannot be revoked, but no government staff has been appointed specifically to enforce protection of the island. Ongoing disagreements between the local Ngäbe bugle Comarca, regional politicians, and the Panamanian government are further complicating long-term protection of the island and the pygmy sloths. Additionally, as pygmy sloths have become more widely recognized internationally, there is growing interest in collecting them for captivity.

CONSERVATION

The pygmy sloth is listed as Critically Endangered as this species has a very restricted range, being found only on one very small island less than 5 km2 in size, and there is likely a continuing decline in the quality of habitat and area of occupancy due to habitat degradation.
Bradypus pygmaeus
is endemic to a single island of Panama, which is protected as a wildlife refuge and is contained within the Ngäbe bugle Comarca. There is a need to improve the enforcement of this protected area. A comprehensive conservation plan is underway, bringing together the local community, wildlife authorities in Panama, and the national and international scientific community to protect the island, using the pygmy sloth as a flagship species.
The pygmy sloth is listed on CITES Appendix II (Notification to the Parties 2013/052, 20 November 2013).

REFERENCES

Additional information and a complete list of references can be found in: Superina, M., T. Plese, N. Moraes-Barros and A.M. Abba (2010): The 2010 Sloth Red List Assessment. Edentata 11(2): 115-134. This article is available here. For information about the latest assessment of this species, please visit The IUCN Red List of Threatened Species.

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