Island Conservancy Tries Contraception to Cull Herd Popular With Tourists but Tough on Plants

AVALON, Calif. – Conservationist Carlos de la Rosa still likes to see buffalo roaming Southern California’s famed Santa Catalina Island.

Just not so many of them.

His employer, the Catalina Island Conservancy, has taken hardcore positions with all kinds of other nonnative animals, including goats and pigs.

But earlier efforts to rid island canyons of goats and pigs sometimes involved hiring sharpshooters to hang from helicopters and pick them off. They turned out to be public-relations disasters.

This time, conservancy officials are turning to a more high-tech solution: bison birth control. For weeks, conservancy staff members have been laying trails of alfalfa to lure bison into pens in the island’s Cape Canyon. Starting Friday, they plan to inject females with porcine zona pellucida, or PZP, a vaccine that works by creating antibodies that glom onto eggs, blocking fertilization.

The bison descend from 14 animals that were brought to Catalina in the 1920s. The local newspaper, the Catalina Islander, reported they were to be used in filming the 1925 silent movie “The Vanishing American.” In those days, chewing-gum magnate William Wrigley Jr. owned the island and encouraged movie shoots there.

The bison took to their new home — and multiplied. By the 1960s, the Catalina herd numbered as many as 600.

In 1972, descendants of Mr. Wrigley created the conservancy and gave it control of 88% of the island, with the mission to protect and restore it. The conservancy continued to thin the bison herd, as an island-management company had been doing.

But the culls, which mainly involved shipping bison off to livestock auctions, angered animal activists, and prices have declined in recent years.

A few years ago, the conservancy started sending spare bison to Indian reservations in South Dakota, where some islanders have traveled to visit them. Meanwhile, the cost of bison transfers kept climbing: The last roundup, earlier this fall, cost close to $100,000.

The weeks it took to move the animals took their toll on conservancy staff, too. “This is not like cowboys and Indians,” says Mr. de la Rosa, the group’s chief conservation officer. Because of Catalina’s narrow canyons and rough topography, “you can’t just get on a horse and herd ‘em.”

Cattle guards and fences generally keep bison away from Avalon, Catalina’s biggest city, and another fence shuts them out of the northwestern part of the island and a smaller village called Two Harbors. But elsewhere, they roam freely and are doing all sorts of damage. They trample delicate native vegetation. They like to roll on the ground, creating bare patches of earth that blow away in the wind. They knock down protective barriers aimed at keeping another invasive species — deer — away from threatened ironwood trees.

Catalina, which has more chaparral and scrub than it has grass, isn’t all that great for the bison. “They’re nutritionally more challenged,” says Mr. de la Rosa, who says that is why the bison here typically don’t grow as big as their Great Plains cousins.

But tourists get a kick out of seeing them, anyway. Holly Shepherd of Poulsbo, Wash., says knowing she would pass bison on the route helped add to the allure of the Catalina Eco-Marathon she ran on Nov. 14. Susan Price of Long Beach, Calif., says she has visited several times and still can’t get over “just having bison here in Southern California.”

On windswept Catalina, population 4,000, “there’s a tenuous, fragile economy that depends on tourism,” says Mr. de la Rosa, noting that bison take on a starring role on tours several companies operate. “The bison is a national icon, and it’s become a Catalina icon as well,” he says.

That is why the conservancy wants to keep some bison hanging around. If the herd is kept to 150 or so, Mr. de la Rosa says, its negative impact on the island will be minimal. But many more than that and the conservancy’s efforts to support native flora and fauna will be adversely affected. Catalina is home to dozens of plants and animals found nowhere else.

Hence, the birth control. Standing on a platform overlooking pens holding the two dozen or so bison the conservancy had rounded up a week ago, Mr. de la Rosa waved a bag of syringes and ear tags. While his staff is administering the first doses of PZP by injection, subsequent boosters will be delivered by darts. “You get close enough, and then you just pop her in the butt,” he says.

After the first year, one dose every 12 months is all it takes to keep PZP working, he says. If the bison population starts getting too low, the conservancy can reduce the numbers of females that receive the vaccine. The program will cost roughly $200,000 over five years, with the group In Defense of Animals picking up a quarter of the tab and the Offield Family Foundation paying another $107,000.

“We want animals to be free,” says Bill Dyer, regional head of In Defense of Animals, which helped raise the money to repatriate some of the island’s bison to the Plains. But given that the conservancy is determined to reduce bison numbers, contraception “is the next best thing.”

Some longtime residents question the conservancy’s mission. “Evolution is a natural process,” says Bart Glass, a real-estate broker who misses hunting the goats and pigs that populated the island until the conservancy kicked them out.

Islander Becky Tamayo says she cried as she watched the latest shipment of bison setting sail for the mainland. “They weren’t bothering anybody,” she says, admitting that she prefers the bison to rare plants.

Some residents find efforts to cut the number of bison quixotic, given the damage done by the 1,000 or so non-native deer on the island. But unlike the bison, the deer are regulated by California’s Department of Fish & Game, which complicates efforts to reduce their population. Currently, state officials allow an annual deer-hunting season capped at 500 animals, no more than two per hunter; last year, hunters killed half that quota.

But the conservancy believes it is obliged to do what it can. “We’re trying to go forward,” says President Ann Muscat, hoping to preserve the biodiversity “that makes Catalina special.”

Wrong move, says Mr. Glass. “You had something special,” he says. Stripped of goats, sheep, pigs and now hundreds of bison, Catalina “looks like the rest of Southern California.”

The Wall Street Journal

The Catalina Island Conservancy has been rounding up the herd so females can get a reversible contraceptive vaccine. The goal: Control the size of the herd to keep it and the environment healthier.

Reporting from Avalon – Half a dozen men with walkie- talkies and cattle prods set out on foot at sunrise Thursday to coax a herd of 10 feral bison into a corral a mile away at the bottom of a Santa Catalina Island valley.

It wasn’ t easy. In the final days of the mating season, a massive bull kept one beady eye on his cows, all of them pregnant, and the other on his human pursuers, who followed close behind shouting and waving their arms as the animals lumbered up steep slopes and into plunging ravines.

It was one of several herding operations that will culminate today with the inoculation of female bison older than 2 years, part of an experimental program designed to limit the population through contraception. The goal: reduce herd size – - which increases by 15% or more each calving season – - to a manageable, healthier, less environmentally damaging and constant 150 or so.

The vaccine is non- hormonal and will not harm the animals or change their social structures, said Carlos de la Rosa, the conservancy’ s chief conservation and education officer. It is also reversible after about a year.

“Bison will continue to be bison,” De la Rosa said. “Males will continue to compete for females, and females will continue to go into heat. The only difference is that we can control how many calves they have.

“For bison in love,” he added with a laugh, “this means romance without responsibilities.”

The Catalina Island Conservancy, a nonprofit organization that owns 88% of the island and is charged with preserving its wild state, believes the program will be a cost- effective, socially acceptable and humane method of controlling the herd. In Defense of Animals, an advocacy group, agrees and has donated a quarter of the cost of the $200,000, five- year program.

The idea of using contraception on the bison was first suggested by Debbie Avellana, an Avalon shop owner and animal rights advocate who fiercely resisted earlier efforts to rid the island of nonnative goats and pigs.

“I’ m so happy. Our bison don’ t have to be shipped out or killed,” she said, “and they will have more to eat.”

The program involves annual injections of the wildlife contraceptive porcine zona pellucida – - PZP for short. When PZP, derived from pig eggs, is injected, it stimulates the immune system to produce antibodies that attach to sperm receptors on the surface of the female’ s eggs and distort their shape, thereby preventing fertilization.

“This is the last season the females will become pregnant en masse,” said Ann M. Muscat, president and chief executive of the conservancy. Contraception, she said, “is the next evolution of management strategy.”

That kind of talk worries Darrell Geist, habitat coordinator for the Buffalo Field Campaign, a nonprofit group dedicated to protecting the last wild bison herd in the United States at Yellowstone National Park.

“When you intervene with natural selection,” he said, “you are unraveling a very complex relationship among herd animals, particularly among matriarchal females and bulls who compete for those females.”

The island’ s bison are descendants of the 14 shipped here in 1924 to appear in the 1925 silent western “The Vanishing American.” A decade ago, as many as 500 roamed Catalina’ s 76 square miles of rugged mountains, lush valleys, streams and grasslands, where the next- largest natural herbivores are ground squirrels.

Locals have come to cherish the shaggy beasts as living symbols of the island’ s heritage, and they are a powerful attraction for eco- tourists.

Some homes in Avalon, the island’ s tourism and demographic center with a permanent population of about 4,000 people, are festooned with painted images of bison or crowned with bronze bison weather vanes. Gift shops sell furry bison figurines and gold- painted, dehydrated bison droppings.

The Catalina Island Chamber of Commerce & Visitors Bureau sponsored a “Buffalo in Paradise” event in 2003, which featured whimsically decorated fiberglass bison placed outdoors throughout town.

But Catalina only appears to be a hospitable landscape for bison.

In 2003, when there were 350 bison on the island, a scientific survey concluded that “although the bison seem to be doing well, they are significantly smaller than mainland bison, experience relatively low reproductive rates and appear to be in poor nutritional condition, based on blood tests and frequent observations of open sores.”

The health of the bison has significantly improved, conservancy officials said, since the herd numbers were reduced to less than 200 beginning in 2005. They achieved that by sending the bison out for slaughter or to breeding programs elsewhere.

Most recently, however, the animals have been transported, at a cost of $1,000 per animal, to Native American reservation lands in South Dakota to live out their lives.

The study also pointed out that foraging and wallowing bison were trampling native plant communities, altering tree canopies by rubbing against trees, and undermining weed management efforts by dispersing a variety of nonnative grasses through their droppings.

The contraception program is expected to be 90% effective, “so there will be a small percentage that does not respond and becomes impregnated,” De la Rosa said.

In the meantime, the conservancy’ s bison wranglers were clambering over the island’ s rugged terrain Thursday with a goal of ensuring that every big browser gets a blood test and an ear tag – - and, for females, the contraceptive.

By noon, nearly 50 animals had been rounded up and trucked to a holding facility at conservancy headquarters in the center of the island.

“It’ s a lot of exercise for our guys,” said Lenny Altherr, the conservancy’s director of facilities management and trail boss of the roundup.

LA Times

The Catalina Island Conservancy is introducing a contraception plan for its female bison with a vaccine that will control the buffalo population. Bison wait in a holding pens before the vets and scientists can draw DNA samples and give the females the contraceptive vaccine.

In 1924, a film crew moved 14 bison onto Catalina Island for a movie appearance that never came to be.

Not only were the animals cut out of the silent film, they were left behind on the island’s interior, presumably because of cost overruns. The move would leave Catalina with a sizeable herd decades later.

To trim the population that at one point numbered 600, the conservancy that oversees most of the island has sold buffaloes to an auction house and shipped the animals off to South Dakota Indian reservations.

But now, management of the herd will come from a shot of a contraceptive dart.

The Catalina Island Conservancy today will announce the start of a birth control program among female bison that utilizes a vaccine derived from pig eggs – a management strategy that’s said to be cheaper and less stressful for the animals than having them shipped away.

The goal is to reduce the annual growth of the herd from nearly 10 percent to 4 percent, about equal to the annual mortality rate, scientists say. The ideal population would range from 150 to 200 animals, a number that is manageable for the conservancy as it seeks to protect the island’s sensitive ecosystems while ensuring the health of its buffalo herd.

“We really are trying to find that balance between protection of the environment, restoration of the environment and the social and cultural values we believe are so important to our lives,” said Ann Muscat, the conservancy’s president and chief executive officer. “And keeping the bison here is something our board found is important to the community.”

Muscat described the new birth control program as “the next level of sophistication in the management of the herd.”

Having too many of the animals on the island isn’t good for the native plants that can get trampled by the bison, nor is it safe for the buffaloes, which have to compete for food.

The contraceptive has been administered for years among deer, elk, wild horse and other bison populations. But Catalina’s application of the vaccine marks its first use on a wild buffalo herd, said Dr. Jay Kirkpatrick of the Billings, Mont.-based Science and Conservation Center at ZooMontana, which has been training conservancy scientists since the summer.

On Catalina, scientists plan to administer the so-called porcine zona pellucida vaccine annually to female bison over the age of 2. When injected into the muscle of a female, the vaccine stimulates the animal’s immune system to produce antibodies against it.

Those antibodies also attach to sperm receptors on the zona pellucida – a non-cellular membrane that surrounds an egg – and distort the egg’s shape.

Fertilization is blocked because the wall of the egg thickens and the sperm can’t penetrate it, scientists say.

Kirkpatrick, who has been a consultant on the use of wildlife contraception since 1988, said the PZP vaccine has been given to bison for at least 10 to 15 years.

“We know it works. We know it’s safe,” he said. “The only difference here is, we’ve got a semi-free-ranging herd.”

On Catalina Island on Thursday, the conservancy’s Carlos de la Rosa stood beside a set of makeshift corrals at Middle Ranch in the island’s interior, where roughly 40 buffalo wandered about, munching on alfalfa. Conservancy workers used the food to lure both males and females into the pens.

Although only females will receive the treatment, both sexes will have blood drawn, get weighed and receive identifying tags for future research.

De la Rosa, the conservancy’s chief conservation and education officer, said most of the females already are pregnant, but that the inoculation won’t hurt them or their babies. And because it is not a hormonal vaccine, he said it won’t cause them to change their behavior with their male counterparts.

“It’s kind of like love without consequences,” de la Rosa said.

The process can be reversed by not administering the shot to certain animals in subsequent years, meaning they still will have the opportunity to reproduce.

The conservancy in years past has sold its bison to an auction house, which would ship the animals by barge to the mainland, presumably to be sold and slaughtered.

In response to concerns from animal welfare groups, however, the conservancy abandoned that process several years ago.

In 2003, with the help of the organization In Defense of Animals and Catalina resident Debbie Avellana, the conservancy made plans to send truckloads of bison to a South Dakota reservation, where they would be able to live out their lives.

There have been two other shipments to reservations since then and, depending on the vaccine’s effectiveness, the conservancy could continue those partnerships. But most people involved acknowledge there is a downside.

Conservancy officials and animal welfare advocates say the process can be taxing for the buffaloes, which are loaded into trucks and shipped away on a barge.

And while the birth control program involves a $200,000 investment over the next five years, it is cheaper than shipping the bison away when the population swells. Just last month, Muscat said, 150 of the animals were sent to a reservation at a cost of about $100,000.

At $24 per dose, the PZP shots will be more cost effective in the long-run than having the animals relocated.

The program comes as welcome news to In Defense of Animals, which wanted the conservancy to manage the bison population in a way that ensures the animals won’t be killed.

The organization has agreed to chip in a quarter of the inoculation costs over the five-year period.

Bill Dyer, IDA’s Southern California regional director, said the birth control plan has advantages over corralling the buffaloes for a ride to the mainland.

“The expense of it, and the stress it puts on them,” he said, “all of that is over now.”

Contra Costa Times