Rare yellow-legged frogs are returned to drought-hammered San Gabriel Mountains
San Gabriel Mountains, in north-central Los Angeles County, were once a lush green jungle, home to a variety of wildlife. They are being reshaped now into one of the most highly developed areas of land anywhere on Earth. Trees and other plants have to make do with less water than the people who live there and rely on them for their livelihood. To survive, the plants have to suck a lot of water from the ground with their roots instead of taking it up through their leaves. Because of this, the soil is becoming less fertile. And the frogs that live there are one of the prime targets of the process.
To see how the yellow-legged frogs are coping, biologist Richard Schapel and his colleagues used GPS collars to trace the animals’ movements and recorded their presence in the area. When the scientists analyzed the data, they discovered that most of them were not there at all. Instead, they found that some of the frogs had dispersed from several previously surveyed sites to the surrounding areas to find a new home. The new places were even worse for the frogs than the original ones.
The scientists observed that the frogs had moved their breeding sites away from the surrounding areas to better find water sources. When they followed the animals’ movements over months of tracking, the team observed a pattern that was consistent with a frog’s ability to disperse from its breeding site. The team also determined that the frogs were more likely to disappear completely in areas that had been under long-term drought.
The findings were published in a recent issue of the journal Proceedings of the National Academy of Sciences.
“It is clear that the yellow-legged frogs are adapting to a new way of life in California,” said Schapel, a research scientist in the Department of Biological Sciences at UC Riverside. “It’s a really interesting adaptation–the frogs seem to be more flexible in their habitat selection,” he said.
Scientists once agreed that the San Gabriel Mountains ecosystem was more complex than initially thought. In the late 20th century, when the scientists