"These incidences are disturbing and raise questions about why this fungus is proving so deadly at this time and what other factors might be at work behind the scenes," Secretary Babbitt said. "We need to better understand the inter-relationships in this environmental puzzle and what we can do to fix the situation."
Chytrid fungus in amphibians was first identified in 1998 by Green and other researchers from the U.S., Great Britain and Australia, who discovered that this fungus had been responsible for large amphibian die-offs in Panama and Australia. The fungus also has been identified in some amphibian populations in Arizona and has caused the death of many zoo-kept amphibians in the United States.
Scientists don't know how this fungus is transmitted from one area to another, let alone why the fungus is affecting amphibian populations around the world. Whether the chytrid fungus is responsible for the frog or toad mortality or the declines of frogs and toads in many western states is still unknown. Green emphasizes that diagnostic tests on the boreal toads are still being completed, and that additional infectious diseases or other possible causes of death may yet be found in this population. Because fungal infections are often considered secondary infections in other vertebrates, USGS is completing further tests for viruses, parasites and bacteria to rule out other factors that could predispose the animals' susceptibility to the fungus.
Two other Colorado populations of boreal toads in Rocky Mountain National Park
have also undergone serious declines this summer and previously in 1996,
according to zoologists at the USGS Midcontinent Ecological Science Center
in Fort Collins, Co., who have been studying these populations for the past
9 years. Although dead or dying toads have not been found in association with
Contact: Paul Slota
United States Geological Survey