Sun Bears: “Bearly” Hanging On

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Sun bear youngster Pagi

The sun bearis a bear species noted by the IUCN (International Union for Conservation of Nature) to be vulnerable to extinction. This rare bear is thought to have declined more than 30 percent in the last 30 years. Primary factors in the decline of the species are deforestation and, to a lesser degree, commercial exploitation of the bears for body parts.

Deforestation is rampant throughout much of the sun bear’s Southeast Asian homeland. In some places, the bear has been completely eradicated, as no suitable habitat remains. Despite this, no countries that comprise the historical range for the species have any active conservation measures in place to aid the sun bear. This stands in contrast to the giant panda, a bear that is listed as endangered but has numerous reserves set aside and a number of legal protections within China.

Of the two subspecies of sun bear, the Malayan and the Borean, the Species Survival Plan (SSP) of the U.S. consortium of members of the Association of Zoos and Aquariums (AZA) has chosen to focus on Bornean sun bears. These bears are perhaps more at risk due to the alarming rate of habitat destruction in Borneo: palm oil plantation farming, forest fires, and illegal lumber extraction are taking their toll. In 2007, the United Nations (UN) estimated that 73 percent of all logging in Indonesia is illegal and was taking place within national park boundaries. The UN predicted that 98 percent of current habitat would be gone by 2022.

To attempt to develop a breeding population of Bornean sun bears, the SSP imported 20 adult bears to the U.S. from Borneo about 10 years ago. These founder bears were primarily animals that had been confiscated from the pet trade or had otherwise been orphaned. It was hoped these animals could reproduce in U.S. zoos to hedge against extinction. Any focus by AZA institutions on the Malayan subspecies was set aside so that all resources could be brought to bear on behalf of the Borneans.

Siblings Palu, left, and Pagi

The San Diego Zoo is fortunate to house 3 Bornean sun bears: a female, Marcella, and her twin 16-month old cubs Pagi and Palu. She and her mate, Dibu, now at the Columbus Zoo, have successfully added four cubs to the U.S. contingent of Bornean sun bears. Unfortunately, no other Borneans have reproduced successfully since they arrived stateside. A variety of issues have hindered the breeding efforts, from aggressive behavior of mating pairs to individual health issues. But the work continues.

In the future, the SSP will shift another male to the San Diego Zoo in an attempt to breed Marcella with a male not yet represented in the next generation. Dibu, it is hoped, can do the same in Columbus. Their offspring Danum may yet breed in Brownesville, where he currently resides. Efforts continue to shake up the breeding pairs statewide to find matches that will be successful. Cross your fingers that the Bornean sun bear, threatened with a very uncertain future in the wild, will be able to find a solid footing in our captive breeding population.

Suzanne Hall is a senior research technician for the San Diego Zoo’s Institute for Conservation Research.