Employing birth control to tame urban wildlife

There were too many squirrels in Santa Monica and too many pigeons in Hollywood.

But rather than thinning out their ranks with the traditional technique of killing off the excess, the two communities decided earlier this year to try a more humane, yet experimental, method: birth control.

Nature being nature and bureaucrats being bureaucrats, the results were decidedly mixed.

Ground squirrel overpopulation in Santa Monica’s Palisades Park -- and how the city has exterminated the rodents to be in compliance with Los Angeles County standards -- has been an issue for the beach-side community for more than 20 years.

After years of killing the creatures by gassing or euthanasia, Santa Monica had hoped to avert another outcry from the animal rights community. The city had been selected to participate in an experimental study with the U.S. Department of Agriculture to give the contraceptive GonaCon to the Palisades Park ground squirrels.

Santa Monica would have been only the second city in the state to participate in the squirrel birth control program. In Berkeley, where the first trial was successfully conducted in 2004, the ground squirrels’ birthrate was cut by 66%, Alameda County and USDA officials reported.

But in late April, Palisades Park was disqualified by the USDA because the park was too small for the study to be conducted, said Gail Keirn, spokeswoman for the agency’s National Wildlife Research Center.

The city was dejected and back to square one. Then in August, the county inspected again and told the city that it had too many squirrels. The county and state consider squirrels to be rodents, like rats and gophers, that can destroy vegetation and carry fleas with diseases such as the plague.

If county inspectors count about two to three ground squirrels visible at any one time per acre of property, they can cite a homeowner, business or municipality. Palisades Park has been cited five times since 1998.

After county officials made their pronouncement, about 45 Santa Monica squirrels were trapped, euthanized and fed to hawks, said Joe McGrath, the city’s parks chief.

Birth control in Hollywood is another story.

The pilot program to get pigeons on the pill is well underway, with $50,000 in donations pledged from area business improvement districts and concerned residents, said Laura Dodson, president of the Argyle Civic Assn., the Hollywood neighborhood group leading the effort.

Since August, some of the area’s estimated 5,000 pigeons have been eating pill-shaped kibble known as OvoControl P from feeders on rooftops, making Hollywood the first area to try the contraceptive since it was given state approval in late July. (OvoControl P has been registered with the state Department of Pesticide Regulation and the U.S. Environmental Protection Agency.)

About 300 pigeons flock every morning at daybreak to eat up the contraceptive kibble, which contains nicarbazin, an ingredient that stops an egg from developing. There are plans to add more feeders next year.

Pigeon overpopulation is a nuisance because the birds roost on utility lines, tree branches and elsewhere, depositing their droppings on cars, buildings and even residents. Their excrement has caused thousands of dollars in structural damage, Dodson said.

“We’ve still got plenty of poop around, but I think with the numbers showing up at the feeders, the birds won’t be as much around next year,” Dodson said.

The pilot program is expected to start showing results within a year, as long as the pigeons consume the kibble once a day. If proven as effective as in previous studies, Hollywood’s pigeon population is expected to shrink by at least 50% by 2012, according to the contraceptive’s manufacturer.

In the past, government agencies have usually killed animals when they overpopulate an area.

But thanks to a growing pharmacopeia of birth control for animals, some wildlife agencies, zoos and even neighborhood groups, such as the Hollywood association, are finding contraceptives a welcome compromise. Both the Humane Society of the United States and People for the Ethical Treatment of Animals have thrown their support behind experimental studies with OvoControl P and GonaCon.

The state of California is helping lead the research through experimental projects at Berkeley, Hollywood and Point Reyes National Seashore, said Keirn, of the USDA.

At Point Reyes National Seashore, about 25 miles north of San Francisco, park officials used to thin herds of nonnative axis deer and fallow deer by shooting them, but stopped in 1994 after the public complained, said Natalie Gates, a Point Reyes wildlife biologist.

Park biologists were concerned about the nonnative deer because they dig up the landscape, are capable of carrying exotic diseases and compete with the native black-tailed deer and tule elk for food, water and shelter.

In November 2006, after more than a decade of debating how to control the population, the National Park Service approved a controversial plan to eliminate all of the park’s deer by killing off about 225 axis deer and many of the 850 fallow deer by 2021.

Under the same plan, some of the female fallow would be spared so they could be part of a USDA experimental study for deer contraception, but they would naturally die off. This summer, 80 does were injected by darts with GonaCon, the same contraceptive planned for use on Santa Monica’s squirrels.

Animal contraception isn’t always an option. At Channel Islands National Park, located 18 miles off the Ventura County coast, park officials decided in 2005 to kill all of its 5,000 feral pigs on Santa Cruz Island during a 14-month period ending in July 2006.

The park did so despite the objections of the Humane Society, and a still-pending lawsuit filed in June 2005 by the Mill Valley-based animal rights group In Defense of Animals, which urged that the pigs be put on birth control or sterilized. But Kate Faulkner, chief of natural resources management at the park, defends the decision.

“There’s nothing on the market close to being successful in the contraception or sterilization of the feral pigs,” Faulkner said. “Most contraceptives are not a one-time deal, and capturing all these pigs would be unlikely. And, anyway, we’re not at the point where we have contraceptives for every animal.”

Animal wildlife experts point out that humans can contribute to the overpopulation of animals. In the case of urban wildlife such as deer, pigeons and squirrels, humans shouldn’t feed them, as that usually fuels more breeding, said John Grandy, a wildlife biologist with the Humane Society.

“We don’t see animal birth control as a silver bullet to overpopulation,” said the USDA’s Keirn. “But there is an emerging new generation of animal contraceptives, and I hope its promise is something humans can comprehend.”

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francisco.varaorta@latimes.com