Hard Lessons in the Tale of the Fox and the Shrike
A strange and perilous balancing act is being played out on San Clemente Island, where scientists say they are forced to kill a rare fox to save an even more endangered bird.
That decision has unleashed a bitter clash over the legal, scientific and ethical questions about wildlife at the edge of extinction.
Some scientists, warning that many birds, foxes and other living things soon will disappear from Earth, say these are questions that could multiply rapidly in the next century. The bird-versus-fox scenario could become common, the scientists say, as we are forced to choose which threatened creatures in troubled habitats should be saved.
Harbingers of such a stark future are everywhere on San Clemente Island, a snippet of U.S. Navy land 65 miles off the Southern California coast.
The Navy is spending $2.3 million this year trying to save the federally protected San Clemente Island loggerhead shrike, one of the rarest birds in North America.
Rats, wild cats, ravens and hawks crave the bird as food. Its natural enemies also include a rare state-protected fox that, like the bird, lives only on the rocky island.
Only 13 of these shrikes are known to remain in the wild. For the bird to survive, experts say, some foxes must die. That decision led to the killing of 15 island foxes this spring, out of about 650 to 700 on the island. Many experts say they know of no other case where a state-protected animal has been killed to aid one protected by the federal government.
The control program has been put on hold, but it raises troubling questions for many.
“Are we going to have to keep making choices? Do we like the ones that are furry? The ones with pretty feathers?” asked David Garcelon, a wildlife biologist working with the Navy to protect the shrike.
He and other scientists are uncomfortable with this life-or-death decision. Passions are running so high in this debate that one professor even equated the fox control program to ethnic cleansing.
Ideally, the experts say, we should learn to preserve rare creatures and their natural habitats long before their populations plummet to intensive-care status.
But with more than 250 California animals and plants already rare enough to get federal protection--more than in any other state but Hawaii--the age of species triage is upon us.
That this drama should unfold on an island is only fitting.
Islands often are homes to unique plants and animals, genetically set apart from mainland species. Some of them, like the foxes, are smaller than their mainland relatives. Sometimes they are more vulnerable to disease, to disturbance of the vegetation that provides food or shelter or to predators from off the island.
“The smaller the island, the higher the extinction rate,” said UC San Diego professor Ted Case, an expert on island biology. “Once you go mucking things up, as humans do, that often brings them over the top.”
That consequence is evident in the meadows and rocky canyons of San Clemente Island, which the Navy uses for bombardment practice.
Although some shelling has sparked wildfires on the island, the shrike nesting grounds in China Canyon are out of bounds as a target. The real villains propelling wildlife toward extinction were the herds of nonnative goats, tens of thousands of them, that for decades gnawed the slopes nearly bare of vegetation.
Over 19 years, the Navy shot or trapped many of the goats in a program opposed by some animal rights activists.
The goats are gone now, but the damage lingers. The island remains nearly treeless, offering little shelter for the imperiled shrike. Only now are native grasses and sages sprouting on the hillsides.
Raising Shrikes in Cages
San Clemente Island is home to 10 federally listed rare plants and animals, and another 28 species are being considered for listing.
This is biology as Lewis Carroll might have written it: Nothing works here quite as it’s supposed to work in nature.
Scientists are trying to raise some shrikes in large condominium-style cages.
The birds’ keepers dyed the breast feathers of one caged male magenta to set it apart from the females. Nearby, eggs lie in incubators. When the chicks hatch, scientists will nourish them with such dainties as sliced and diced bits of frozen mice.
This breeding program is the most striking life-support system on the island. Run by the San Diego Zoo, its goal is to create what the Navy’s regional director of natural resources, Jan Larson, calls “a reservoir in case the wild population indeed goes extinct.”
But captive breeding is a highly uncertain science. Since the program began in 1991, 40 shrikes have been released to the wild. Most died within a few days. None lived longer than eight months.
“We’re definitely on the cutting edge in terms of having to learn and develop things,” said Pat Witman, animal care manager at the zoo’s Avian Propagation Center. “There’s no textbook written on this.”
This spring may bring some good news. Two captive-bred females have been matched with males in the wild. The tally of captive-bred shrikes as of last week: 54 birds, including those hatched this season.
“This is probably going to be our best season yet in terms of captive breeding,” Larson said.
But in China Canyon, the future of the birds is uncertain.
The number of shrikes in the wild has dropped from 35 in 1994 to 20 in 1996 and 1997, 14 in early 1998 and only 13 today.
“The 1998 population was four [wild] females away from extinction,” federal wildlife control biologists wrote five months ago in a report urging stepped-up controls of creatures that eat shrikes, their eggs and their babies.
The Navy long has been controlling the cats, rats and ravens that prey on the shrike. But it approached the foxes more gingerly. Last year, for the first time, foxes were trapped and equipped with “shock collars.” The collars give the foxes a mild electric shock if they approach trees where shrikes are nesting.
But after further study, scientists aiding the Navy decided that the collars weren’t effective enough; some foxes would have to be removed from the island or killed.
Killings were bound to be controversial, since the island fox itself is listed as threatened under the California Endangered Species Act. It is not covered by the federal act, which grants certain creatures, including the shrike, more stringent protection.
Like ‘Making a Zoo in the Wild’
Several experts with the U.S. Fish and Wildlife Service, which enforces the federal act, said they know of no other case in which a state-listed animal has been killed to aid a federally listed creature.
In Hawaii, only seven birds known as the ‘alala--or Hawaiian crow--remain in the wild. Their natural predators include the endangered ‘io bird, which numbers about 1,200 and has been known to kill young ‘alala. The endangered California least tern is prey to the rare peregrine falcon, subject of a widely publicized restoration effort.
The shrike and the fox have probably coexisted on San Clemente Island for thousands of years. Only now is the shrike threatened by the fox, in an ecology woefully out of balance.
To the frustration of many, the focus on San Clemente has been on saving the shrike, not restoring the vegetation.
“In conservation circles, you just don’t dismantle an ecosystem to save just one species. It’s as if you’re making a zoo in the wild,” said Robert Wayne, a UCLA biology professor who is an expert on foxes.
But though federal and state officials say they too are torn by the decision to kill foxes, they point to the plight of the shrike.
“Given the number of foxes on the island, it’s the lesser of two evils,” said Susan Cochrane, chief of habitat conservation planning for the state Department of Fish and Game.
The Navy has moved ahead with plans to remove up to 50 foxes a year, using a “two-strikes” rule: Foxes that cross the “shock collar” electrical barrier more than once are doomed.
The tally so far: 15 foxes killed by lethal injection and eight shipped off to zoos. The dead foxes included four lactating females that apparently left orphaned pups in the wild.
Then came reports this spring from the Channel Islands National Park to the northwest. Cousins of the San Clemente fox, many of them, have been dying under mysterious circumstances. On San Miguel and Santa Cruz islands, the number of foxes has plummeted 90% in four years.
Scientists are perplexed. They think that golden eagles may be at fault, or heartworm, or some unknown disease. The foxes’ deaths, scientists say, illustrate how little is known about what makes species thrive or falter.
The fox control effort has been halted temporarily on San Clemente to give scientists time to determine if the killings are still needed. More foxes may have to be killed later this spring when shrike fledglings emerge from their nests and are most vulnerable to predators.
But the Navy may try another approach--trapping all foxes found within the nesting area and holding them until the fledglings mature. The foxes would then be released.
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On The Brink
The bird known as the Sam Clemente Island loggerhead shrike is fast approaching extinction, with only 13 wild birds remaining on Earth. The U.S. Navy is fighting to keep the birds alive, guarding wild nests electronically, raising some birds in captivity and killing predators.
Source: U.S. Navy
