FOR IMMEDIATE RELEASE (April 15, 2008)
Amphibians: Life Under the Leaf Opens April 26

Dallas Zoo Taking Action for Year of the Frog

Irrefutable scientific evidence, gathered over more than a decade, has proven that amphibian species are currently becoming extinct on a global scale. To raise awareness, the Association of Zoos & Aquariums (AZA) has designated 2008 as Year of the Frog and the Dallas Zoo is highlighting the amazing diversity of this unique group of vertebrates as well as educating the public on why they are in trouble. A special exhibit, called Amphibians: Life Under the Leaf features several endangered and threatened amphibians. This special exhibit will open on April 26, the second weekend of Dallas Roars! presented by Kimberly-Clark Corporation.

“This crisis is one of unprecedented proportion,” said Ruston Hartdegen, curator of herpetology for the Dallas Zoo. “The Global Amphibian Assessment reports that approximately one-third of all known amphibian species are threatened. That is more than all known threatened mammal and bird species combined.”

A recent population assessment found that of the 6,000 frogs, salamanders, and caecilians described, 32 percent are believed to be threatened with extinction and 165 amphibian species may have already been lost to extinction.  Frogs, especially, are completely vanishing at a rate never seen before. Some of the causes for these declines include habitat destruction and fragmentation, introduced species, emerging infectious diseases, pollution, and climate change.

“People don’t realize the important role amphibians play in ecosystems worldwide,” said Jessie Crowley, amphibian keeper at the Dallas Zoo. “Amphibians prey on insect populations keeping them down to manageable numbers, which is important in controlling insect-borne pathogens like malaria.”  

The major culprit of amphibian population declines has historically been habitat loss and degradation. However, water quality debasement due to agricultural run-off has negatively impacted the habitat of amphibians.

Most recently, many of the declines and extinctions are now attributed to the rapidly dispersing infectious fungus called Batrachochytrium dendrobatidis (“Bd”), which is commonly referred to as chytrid. “It was in the late ‘80s to early ‘90s that biologists started to notice a precipitous decline in amphibian populations even in seemingly protected areas,” Crowley said. Mass die-offs of amphibians, where more than 50 percent of species were extirpated within 4 to 6 months, while the remaining species persisted at approximately 20 percent of their normal abundance, had been seen in upland regions of Central America. However, evidence linking these die-offs to the arrival of chytrid was not documented until recently.

The combined effect of habitat destruction, climate change, pollution, invasive species, and chytrid cannot be addressed solely in the wild. Zoo and aquarium breeding programs have become the only hope for many species faced with imminent extinction.

“Zoos can play a major role in curbing amphibian declines through the captive breeding programs and providing sanctuaries for threatened species,” Crowley said.

“We also have decided to focus a lot of effort on our own backyard,” Hartdegen said. “We are working with native Texas species like the Texas blind salamander and Houston toad, as well as assisting in international programs.”

Amphibian specialists are working toward developing captive assurance colonies for the elusive Texas blind salamander, a cave-dwelling caudate found only in Texas aquifers. The Dallas Zoo, using the breeding laboratory at The Dallas Aquarium at Fair Park, was the first Zoo to breed Texas blind salamanders in captivity. 

Dallas Zoo amphibian keepers are conducting surveys of black-spotted newt populations in South Texas to determine whether they are at risk of declining. Without an accurate count of the population, herpetologists cannot determine the status of the species.

For more information:

• AZA Year of the Frog Information
• Amphibian Ark Program
• The Global Amphibian Assessment