While there is scant scientific data to explain the increase, agriculture and wildlife experts generally attribute it to laws severely restricting the trapping and hunting of coyotes and mountain lions.

Dr. John Maas, a University of California Cooperative Extension veterinarian specializing in beef cattle, said the report was no surprise.

"Everybody has observed the same thing in California," he said. "I think those numbers are pretty accurate of what's going on out here."

Specifically, the Cattle Predator Loss report issued by the National Agricultural Statistical Service said that in California, 14,900 adult cattle and calves were killed by predators in 2000, nearly three times more than the 5,600 killed in 1995. Killings of calves, the primary targets of predators, increased more than threefold over that period, estimated at 12,500 last year, up from 4,100 five years earlier.

In contrast, nationwide cattle predation rose about 25 percent over the period, reaching an estimated 147,000 in 2000, up from 117,400 in 1995. The latest report pegged the 2000 economic impact at $51.6 million.

The federal official primarily charged with controlling damage caused by wildlife in California said he, too, was not surprised that predation losses had increased, although it was more than he expected.

"I couldn't say specifically why California stands out. I don't know of any specific scientific studies that would lead us to that answer," said Gary Simmons, state director of the U.S. Wildlife Services (USWS) program. USWS is an agency of the U.S. Department of Agriculture.

Still, he noted, his agency's efforts were hampered by the 1998 passage of Proposition 4, which banned the use of steel leg-hold traps and a sodium-cyanide device that was particularly effective against predatory coyotes.

"Just the loss of ability to capture and control coyotes would have to play into it," Simmons said.

Coyotes were the primary predators, the study found, accounting for more than three of every five cattle losses in California last year. Mountain lions were second, at about one in five cattle kills, and dogs accounted for about one in 10.

Duane Martin Jr., president of the San Joaquin-Stanislaus Cattlemen's Association, agreed that the ban on steel traps and the cyanide devices is to blame.

"There's nothing I can do about the population of coyotes, so they're killing calves all the time," Martin said. "This fall, we had a pack of 10 of them kill a 500-pound steer."

Alternate methods of coyote control are far less effective, said Russell Mason, director of USWS's Predation Ecology Field Station in Logan, Utah, and professor of biology at Utah State University and the University of Pennsylvania.

"All of the nonlethal methods we've developed are specific for sheep protection; almost none of them work with cows," he said.

Mason also suggested that increasing urbanization in California may help boost coyote populations by providing an optimal habitat. Suburbs provide coyotes plenty of cover, water, food, and protection from hunting and other pressures.

"There are lots of people who feed coyotes, because they think they're cute," Mason said. "Suburban dwellers are providing pretty good for coyotes."

As an example, throughout the West, populations of coyotes might average 0.6 animal per square mile. In south Texas, a particularly good habitat, densities might get to four animals per square mile. In a survey of a military base in the San Diego region, Mason said he found six to eight coyotes per square mile.

The experts also suggested that the decline in the state's sheep industry, as well as a decline in wild deer populations, may be forcing the predators to turn to other prey, including cattle.

A 1990 state ballot measure, Proposition 117, which largely restricted the hunting of mountain lions, also may be a contributing factor, although there is no definitive evidence of this.

Martin said California's largely urban populace doesn't understand the problems faced by ranchers and other agricultural interests.

"In this state, we don't have as much of a voice, because there's not as many of us as live in town," he said. "Until the coyotes and mountain lions start eating some kids. ... it's not going to change."

And he said that's bound to happen as the population of wild predators increases while subdivisions intrude more and more into former wildlands.

Franz Rulofson, a UC Cooperative Extension farm adviser in Sonora, said he wasn't sure how to explain the sharp increase in cattle predation, but it does raise a flag.

"It's a problem. It just goes to tell you we need to manage the predators better than we have been."