The first hands-on rearing of a critically endangered white-bellied heron in Bhutan was successful thanks to a pair of bird experts with the San Diego Zoo Safari Park who spent three months in the small Asian nation this year, park officials said Thursday.Only 26 of the large wetlands birds are believed to be left in Bhutan and about 50 in the world, according to the park. Bhutan is a land-locked nation between China and India, and lies at the southern base of the Himalayan mountains.In rearing the chick, animal-care manager Don Sterner and lead keeper Debbie Marlow used an incubator, but periodic electrical outages meant that the bird required round-the-clock monitoring. Sterner and Marlow trained local authorities in how to care for the bird."At that time the chick was 40 days old and beginning to stand, learning to fly and catching live fish," Sterner said. "Our hope is to continue to assist the folks in Bhutan who are dedicated to saving this species."The white-bellied heron is mostly dark gray and has a contrasting white throat and belly. Development and pollution have degraded the bird's wetlands habitats.Sterner and Marlow, who collaborated with the Royal Society for Protection of Nature, have extensive experience in the conservation of endangered birds, mostly working with the California condor.