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."
Write to Sarah McBride at sarah.mcbride@wsj.com
No comments:
Post a Comment