Two rare pregnancies spark hope for Sumatran rhinos — but also concerns about inbreeding

Two critically endangered Sumatran rhinos are pregnant at an Indonesian sanctuary, a rare success for a species reduced to a few dozen animals in the wild. The pregnancies also highlight the genetic constraints facing the country’s captive-breeding program. Indonesia’s Ministry of Forestry and the NGO Yayasan Badak Indonesia (YABI), which manages the sanctuary, announced the pregnancies on Oct. 3. A female named Ratu is carrying her fourth calf, fathered by Andalas, while her daughter Delilah is carrying her second calf, fathered by Harapan. Both are due around May 2027. Ratu was captured from the wild in Sumatra in 2005, while Andalas and Harapan, who are full brothers, were born at Cincinnati Zoo in the U.S. in 2001 and 2007, respectively. Delilah was born to Ratu and Andalas at the Sumatran Rhino Sanctuary in 2016 — meaning the father of Delilah’s calf is her paternal uncle. Experts at the Sumatran Rhino Sanctuary seek to pair the least-related males and females possible, Nina Fascione, executive director of the International Rhino Foundation, told Mongabay in an email. They also must consider factors such as differences in body size, she said, but their choices are limited by the small number of rhinos under human care. The 11 animals in Indonesia’s breeding program are the only captive Sumatran rhinos in the world, and all of the males in the program are related. “The current critical situation outweighs the genetic diversity considerations,” Fascione said. Ratu, a captive female Sumatran rhino, is expecting her fourth calf. Image…This article was originally published on Mongabay