More than 100 endangered mountain yellow-legged frogs have died in a captive breeding program in Fresno, California, the Los Angeles Times reports. The 104 frogs died over the past month after recently metamorphosing from the tadpole stage. Experts are still struggling to figure out what went wrong.
“We have two frogs left,” Scott Barton, director of the Fresno Chaffee Zoo, told The Times. “We’re trying to determine exactly what happened.”
It is estimated that fewer than 200 mountain yellow-legged frogs exist in the wild. Native to California’s San Bernardino, San Gabriel and San Jacinto mountains, the species’ population has been dramatically affected by loss of habitat and the introduction of nonnative species such as trout, crayfish and bullfrogs. The frogs are also vulnerable to pesticides and fungal infections.
The frogs at the Fresno Chaffee Zoo were rescued from the San Gabriel Mountains after a devastating fire in 2009. Renowned for its amphibian husbandry, Chaffee Zoo is one of three facilities currently breeding the mountain yellow-legged frog for reintroduction.
In San Diego, experts have encountered similar barriers. Seven adult frogs died at the San Diego Zoo’s Institute for Conservation Research in 2006. Last year, the Institute released 36 tadpoles; researchers have been unable to find evidence of their survival.
“These frogs are very specific in their requirements. What works for one group may not work for another,” said U.S. Geological Survey ecologist Adam Backlin. “The problem is that zoos do not have the space, staff or the funds … [the frogs need] almost constant attention.”
“We were thrown a curve ball with a species that was new to us,” said Barton.
Barton added that the Chaffee Zoo may send its remaining pair of frogs to another facility, “to see if someone else will have better luck.”
Photo credit: USFS Region 5