The decline of amphibian populations worldwide has been documented primarily in frogs, but salamander populations also appear to have plummeted, according to a new study by University of California, Berkeley, biologists.
By comparing tropical salamander populations in Central America today with results of surveys conducted between 1969 and 1978, UC Berkeley researchers have found that populations of many of the commonest salamanders have steeply declined.
On the flanks of the Tajumulco volcano on the west coast of Guatemala, for example, two of the three commonest species 40 years ago have disappeared, while the third was nearly impossible to find.
Frog declines have been attributed to a variety of causes, ranging from habitat destruction, pesticide use and introduced fish predators to the Chytrid fungus, which causes an often fatal disease, chytridiomycosis.
These do not appear to be responsible for the decline of Central American salamanders, Wake said. Instead, because the missing salamanders tend to be those living in narrow altitude bands, Wake believes that global warming is pushing these salamanders to higher and less hospitable elevations.
Missing frogs are easy to spot, Wake said, because they gather in ponds to breed, or they can be caught in the glare of a flashlight at night. Many salamanders, however, in particular the Plethodontid salamanders, which comprise two-thirds of all species worldwide, are secretive, living under logs and rocks. Nevertheless, anecdotal accounts have pointed to a salamander decline and an amphibian decline, in general.
In Guatemala, those salamanders with narrow elevational niches and living exclusively under logs were most affected, while salamander “generalists” able to live in a variety of habitats, from leaf axils and bromeliads to moss mats, bark and burrows in the soil, were in about the same abundance as before. There was little evidence of Chytrid fungus, and habitat quality is generally similar to what it was in the 1970s. A nearby volcano with several of the same affected species is a nature reserve, and surprisingly, only a single salamander was discovered on two trips.
– from eurekalert. 9 Feb 2009