A study by a Sacramento State professor and a UC Davis professor, published in the April issue of the Journal of Ecological Applications, linked pesticides to the disappearance of California red-legged frogs.

Sac State Professor Carlos Davidson co-authored the study with Professor Bradley Shaffer at the Center for Population Biology at UC Davis.

“Amphibians, mostly frogs and toads, have been disappearing worldwide and mostly in California,” Davidson said.

The California red-legged frogs, once found in 46 counties, can only be found in 26 counties today, a loss of 70 percent of its former range, according to the U.S. Fish and Wildlife Service.

“Most people didn?t know why they disappeared,” Davidson said.

The research began in 1997 when Davidson received several scholarships to research why the frogs were declining at such a high rate. Davidson asked Shaffer to join him in the study. The research was finished two years later and it took another two years to publish the results.

Davidson and Shaffer began their research by looking at museum records of past habitat sites of the California red-legged frogs and then mapped the locations. The next step was to gather information on whether the frogs were still at those locations.

With mapped locations of the frog?s past and present habitats, the researchers looked at its surroundings and had to figure out why the frogs disappeared. The analysis showed pesticide and urbanization as the two main factors to the disappearance of the California red-legged frogs.

The decline is due to the increase of pesticide use on agricultural land blowing toward the frog?s habitat.

The analysis of the pesticide affecting the decline of the frogs was a shock to Davidson.

“We figured the urbanization was typical but the pesticide use we didn?t know,” Davidson said.

To protect the California red-legged frogs, the U.S. Fish and Wildlife Service listed the frogs as an endangered species and designated 4.1 million acres in 28 California counties as critical habitats.

Critical habitat is defined by the U.S. Fish and Wildlife Service as specific areas that have been found to be essential to the conservation of a federally listed species and which may require special management conditions or protection.

Whether the results of the pesticide use is a main source to the decline of the frog?s population is undecided but it is a main piece of evidence.

“Annually in California we use a hundred million pounds of pesticide and not all of the pesticide stays where it?s supposed to. We don?t know where the wind blows it into and it may be the most remote parts of the mountains. We don?t know what effect it does have, this study suggests that we should take this more seriously,” Davidson said.