Breeding programs for some threatened species have been successful. However, three-toed sloths are very difficult to maintain in captivity. They often do not survive, nor reproduce. For years, many have tried to maintain them artificially outside the Tropics, and nearly all have failed. According to Dr. Jutta Heuer, from Halle Zoo, Germany, one of the world experts in sloth husbandry in Europe, there is little to no experience with keeping, breeding and feeding three-toed sloths in captivity.

“A modern and serious zoo should never bring wild animals in without knowing this basic information. As studbook keeper for two-toed sloths in Europe I can say that because of ignorance and lack of experiences from zoos, a lot of sloths paid with their lives in the past,” says Heuer.

Recently, the Dallas World Aquarium has been able to maintain a small population of three brown-throated three-toed sloth (Bradypus variegatus) – another sloth species that is not endangered – by providing fresh Cecropia leaves to them flown in from Hawaii. But these three animals are the only ones which survived out of the nine sloths Dallas Aquarium imported from Venezuela and Costa Rica in the past 15 years. The only baby sloth born in captivity died 7 months later and had been conceived in the wild.

To make matters worse, the critically endangered pygmy sloths themselves have never been held and bred in captivity. Even their actual diet is unknown. They are thought to eat primarily red mangroves from the coast, but the radio collar study found pygmy sloths on the interior of the island in deep forest, suggesting that other trees make up at least a portion of their diet.

“The idea of an external breeding program to increase the number of pygmy sloths sounds logical and noble at first, but when you consider that it’s hard enough to just keep common three-toed sloths alive in captivity, let alone breed them, it seems highly unlikely that a satellite breeding population in Dallas would have yielded anything more than at best a few sloths surviving in captivity in a foreign zoo, but more likely eight fewer surviving pygmy sloths in the wild. The potential risks at this time do not justify the means. Promising the local community that by removing a few sloths from the island they will eventually benefit by receiving multiple captive-bred replacements is a fantasy at this point,” says Voirin.

. . .

“We are really worried,” a local resident, who asked to remain anonymous, told mongabay.com. “They said they were going to come back and this time we wouldn’t be able to stop them."