Science leaps forward with Calaveras County frog jump

Biologists test the pros of amphibian athletics

PROVIDENCE, R.I. ― Rumors of the great jumping frogs of Calaveras County have not been greatly exaggerated.

A contestant in the Calaveras County Fair frog jump is about to be set down by his handler. Contestants routinely outjump frogs that have been tested under laboratory conditions, raising questions about both frog biomechanics and the effects of competition pressure on amphibians. Jeff White

The longest jump reported in scientific papers for an American bullfrog is almost 1.3 meters, says Henry Astley of Brown University in Providence, R.I. Yet new measurements have added almost a meter to that record by using California’s Calaveras County Fair as a testing ground for determining maximal species performance. Inspired by a Mark Twain story from 1865, the fair has for 83 years featured a highly competitive jumping-frog contest.

To find out how far frogs can leap in a single bound, researchers had to measure for themselves, because the contest is based on the total distance covered in three jumps.

Contest officials don’t permit scientists to set up equipment in the jumping arena, Astley says. Preserving optimal jump conditions, comparable year-to-year, is a big deal in Calaveras County. Contestants raise intense disputes over matters such as whether a fairgoer heading toward a popcorn stand has distracted a frog at a critical second.

Astley and his colleagues measured jump distance using computer analysis of video from a camera carefully positioned in the viewing area. More than half the 3,449 frog jumps researchers recorded in the 2009 contest beat the record from the scientific literature, Astley reported July 10 at the 2010 Joint Meeting of Ichthyologists and Herpetologists.

Judges at the 2009 contest declared the winning three-jump distance to be 21 feet even, as measured from the starting plate to the point where the frog finally plopped. The Brown team, however, recorded a different frog as covering the most ground on a single jump, a leap of 2.2 meters, or more than 7 feet.

Such great leaps raise issues of biomechanics, Astley said. Calaveras frogs appear to be jumping farther than possible for the calculated power of bullfrog muscles. Astley speculated that the frogs amplify their power by using their leg tendons as a spring, stretching the tendons and letting them snap back all at once.

Most frog jockeys, as human contestants are known, compete using the American bullfrog (Rana catesbeiana), a large, voracious species that has invaded the West Coast from the eastern United States. Jockeys can touch their frogs only at the beginning of the first jump. Afterwards they rely on shouting, blowing or crouching behind the frog and doing their own startling leaps to urge the frogs on.

Anyone can rent a frog at the fair to enter the contest. But many serious competitors bring their own, inspiring rumors about secret locations in the wild for catching a top jumper.

Jockey expertise in locating a top frog and inspiring it matters to performance, according to Astley’s data. Jump lengths of rental frogs showed a roughly bell-shaped distribution. In contrast, nonrental frogs showed a distribution lopsided toward the high end of jump length.

By now the Calaveras frogs may indeed be reaching the outer limits of what bulllfrog species can do, Astley said. Winning jumps tended to lengthen during early decades of the contest but haven’t improved a lot since the 1980s.

“Were the pro frogs tested for steroids?” herpetologist Matt Hinderliter of The Nature Conservancy in Camp Shelby, Miss., asked Astley at the meeting.

No, but a frog-doping scandal would hardly explain all the study results, such as how so many of the rental frogs beat the old “maximum” distance for a jump, Astley said. Analyses of the spread of jump distances recorded at the fair, he said, suggest that scientists need to test hundreds of animals to see anything close to a species’ real maximum performance. And judging by the antics of hard-core frog jockeys, the animal’s motivation matters too.

Susan Milius is the life sciences writer, covering organismal biology and evolution, and has a special passion for plants, fungi and invertebrates. She studied biology and English literature.

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