A NATIVE FROG IS HEARD AGAIN

Scientists use AI to detect breeding calls in Southland, confirming their effort to boost species is a success

- BY JULIE WATSON

A RED-LEGGED froglet peeks out of a restoration pond on a ranch outside El Coyote, Mexico.

The scientist traipses to a pond wearing rubber boots, but he doesn’t enter the water. Instead, Brad Hollingsworth squats next to its swampy edge and retrieves a recording device the size of a deck of cards. He then opens it up and removes a tiny memory card containing 18 hours of sound.

Back at his office at the San Diego Natural History Museum, the herpetologist — an expert in reptiles and amphibians — uses artificial intelligence to analyze the data on the card. Within three minutes, he knows a host of animals visit the pond — where native red-legged frogs were reintroduced after largely disappearing in Southern California. There were owl hoots, woodpecker pecks, coyote howls and tree frog ribbits. But no croaking from the invasive bullfrog, which has decimated the native red-legged frog population over the last century.

It was another good day in his efforts to increase the population of the red-legged frog and restore an ecosystem spanning the U.S.-Mexico border. The efforts come as the Trump administration builds more walls along the border, raising concerns about the impact on wildlife.

The decline

At 2 to 5 inches long, red-legged frogs are the largest native frogs in the West and once were found in abundance up and down the California coast and into Baja California.

The species is widely believed to be the star of Mark Twain's 1865 short story “The Celebrated Jumping Frog of Calaveras County,” and their crimson hind legs were eaten during the Gold Rush. But as the red-legged frog declined in numbers, the bullfrog — with its even bigger hind legs — was introduced to menus during California’s booming growth in the late 19th and early 20th centuries.