ECOLOGY : When No Newts Isn’t Good News

Crouched on a rock slab high in the Cold Creek Canyon Preserve near Malibu, Pepperdine University student Seth Gamradt scoops up an orange California newt that has just snagged a large, struggling spider in the creek.

The newt tries to swim away from Gamradt, but moves too slowly. Its half-drowned prey floats downstream, where it is retrieved by Pepperdine natural sciences professor Lee Kats.

“Newts are basically scavengers,” said Kats, marveling at this newt’s ambition. “They’re not good at catching true aquatic prey, so they hope things fall into the water.” To catch a spider, he said, is beyond most newts’ dreams.

It was a dramatic moment for Kats, 31, who has studied the newts and tree frogs at Cold Creek for four years.

Now, in the wake of the November wildfires, which torched the preserve, ecologists’ interest in the tiny creatures has increased as they study how the California newts survived the fire and what clues they may offer about the overall health of the Santa Monica Mountains.

“More than most amphibians, (the newts) utilize both aquatic and terrestrial habitats,” Kats said. “Given that amphibians have such sensitive skins, they’re very good indicators about anomalous substances in soil and water. If (newts are) around, it’s a good indicator that the health of the land and water is pretty good.”

The preserve, which reopened in mid-May, is lush with new growth and there appears to be an abundance of newts.

Last winter, Kats wondered if the creek’s newt population was wiped out by the fire. That would have been a great loss since little is known about this newt species, one of three found in the state and the only one in Southern California.

But this winter and spring, adult newts made their normal migration from land to the stream in numbers close to previous years, Kats has learned. Because they survived the fire, Kats said, “this really tells us these animals are probably at least a foot underground” when on land.

Kats’ research indicates that newt populations elsewhere in the mountains have been greatly reduced over the last several years, mainly because they are preyed on by such creatures as bullfrogs, crayfish and mosquito fish not found in Cold Creek. Development and the proliferation of hiking trails have also disturbed their habitat.

Although the skin of adult newts contain a powerful toxin that makes them an unpalatable meal, their nontoxic eggs and larvae are eaten by many creatures.

And though newts may be abundant at Cold Creek, there is uncertainty about the future. The stream was severely affected by the fire’s aftermath, with most of the deep pools that newts prefer for mating and egg-laying filled with silt.

As a result, only half the normal number of eggs have been laid this spring and “the females are laying eggs in very peculiar places,” Kats said.

“Normally, you wouldn’t see them lay eggs in anything less than three feet of water. Now they’re laying eggs in pools only six or seven inches deep. That’s risky, if (the pools) dry out” before the fishlike larvae can transform to newts.

Lately, the newts have had one stroke of luck--plenty of earthworms washing downstream with the silt. To a hungry newt, “there’s nothing better than a drowning earthworm,” Kats said.

When he encounters a newt at Cold Creek, Kats sometimes squirts a little water down its esophagus to force the contents of its stomach up. He bags the contents and takes it back to the lab for analysis.

The procedure gives a newt just “a little bit of a bellyache,” Kats said, but “ecologically it tells us a lot.”

This year, Kats has been finding earthworms, not newt eggs, in the animals’ stomachs, indicating that cannibalism has not been occurring.

“Newts are not good at capturing fast-moving prey, so their preferred prey is slow-moving,” Kats said. “Egg masses have filled that role in the past. We think in years when the earthworms are not there they’re making the best of the situation. This year they have other options.”

Peter Morin, a Rutgers University biology professor, has called Kats’ work on cannibalism among newts “cutting-edge” and “fascinating.”

Tiny California tree frogs, another native, are also still abundant at Cold Creek. “My best hunch is they were actually in the water” when the fire roared by, Kats said.