Rat Patrol : Ranger Tries to Turn Tide Against Rodents That Are ‘Overpowering Force’ on Small Isle

Over the last 3 1/2 years, Frank H. Ugolini has spent perhaps 150 nights stalking rats on East Anacapa Island, a rocky, wind-swept speck in Channel Islands National Park.

On about 15,000 occasions, he has gingerly placed raisins, macadamia nuts and, most often, dollops of NuMade Soft ‘n’ Creamy peanut butter in industrial-sized traps known as Victor M-9s. He has set the traps in gullies and in crevices, on the edges of cliffs and in the soft dirt beneath clumps of sage and island buckwheat.

Ugolini, the park’s resource management chief, has never left empty-handed. The rat community is many hundreds of times larger than 90-acre East Anacapa’s human community, which consists of a lone park ranger and some occasional helpers.

In fact, the rats, which apparently swam to the island from shipwrecks as recently as 50 or 100 years ago, have so thoroughly infested East Anacapa that they have driven out the native white-footed deer mouse--the only mammal, and one of just five vertebrates indigenous to the island.

An effort to reintroduce the mice has pitted the National Park Service, which tries to restore land under its control to a pristine condition, against the hearty Rattus rattus, which could care less about pristine. Rats arrived in North America around 1750 and have skittered around the Channel Islands for as long as a century, but, by Park Service standards, they are just off the boat.

“There’s no ecosystem in the world quite like the one we have here, and I don’t see any way the rat can be viewed as a natural part of it,” says Charles Drost, a park biologist. “They’re just such an overpowering force on East Anacapa. I think they’ve got to go.”

The contest between man and rat on East Anacapa typifies a predicament with which the Park Service grapples throughout its 79-million-acre territory. Exotic species, which park officials view as living things introduced to an area after the arrival of the white man in North America, have made destructive inroads in more than 150 parks and monuments, jeopardizing native plants and animals. As a result, 42 native mammal populations have been wiped out at 14 national parks in the West, according to a University of Michigan study.

In the Channel Islands alone, officials worry about many animals that took to the wilds after farmers and ranchers left the islands. Pigs on Santa Rosa Island devour the roots of oaks found nowhere else in the world. Thousands of wild sheep on Santa Cruz Island decimated grasslands until recently, when the Nature Conservancy, which manages much of the island, shot them. On San Miguel Island, a pair of burros abandoned by a movie crew decades ago have spawned a herd of about 75.

Worried About Rats

Eventually, Ugolini says, the Park Service will be forced to hunt or to allow the hunting of the burros and the pigs and the other exotic species in its jurisdiction. But his most immediate worry is the rats, which, for unknown reasons, are far more voracious on East Anacapa than on the other islands.

“There hasn’t been a mouse seen here since 1979,” says Ugolini, “and God only knows what they’re doing to the invertebrates.”

Besides doing in the deer mice, with which they coexist on other islands, rats also are suspected of dining on a rare species of land snail. They can terrorize young sea birds and rampage through delicate tidal pools.

A Park Service document calls the rats “an unsettling presence” on East Anacapa, the closest of the Channel Islands to the mainland and the most frequently visited. They have chewed through new wiring in the ranger’s house and gnawed doors and carpet in the island’s visitor center. They have barged into campers’ tents. One Park Service worker quit after he was awakened by a rat leaping onto his chest.

“If we didn’t do anything, they’d probably just take over this whole island,” Ugolini says. “In another 100 years, we could probably wind up with nothing but rats here.”

Frustrating Task

So Ugolini, a veteran of 30 years in the Park Service, leaves his wife, son, and 82-year-old mother-in-law in their Ojai home four or five nights each month to stem the gray tide.

It is a frustrating task. Rattus rattus breeds every 22 days. Birds devour them from time to time, but members of the species survived a nuclear blast at a test site in the Marshall Islands in 1952.

Unbowed, Ugolini sets out from the East Anacapa ranger station with a basket full of traps just before dusk. He can point out empty snail shells at the mouth of rat burrows, and he knows all the gullies and culverts most frequented by rats on their nightly expeditions for grubs, roots, lizards and other edibles.

“We always get lots of action in the culverts,” he says.

From the Coast Guard lighthouse at the island’s eastern tip to an outcropping called Coreopsis Point a half-mile away, Ugolini treads carefully, picking his way around clumps of native vegetation. He speaks with regret of the seven or eight meadowlarks that have strayed into his traps over the years, and gives the general impression of a man more comfortable studying the rat than bashing its head in.

He has packed three handwritten volumes with data about the 997 rats he has captured. He chronicles their length and weight, which he measures after his post-dawn rounds of the traps. He also keeps notes on the state of their sex organs, because some scientists believe juvenile animals become sexually active when their community’s survival is in doubt.

But, for all the data about them--and the fact that some immature rats do appear to be mating--the rats continue to thrive. Ugolini harvests more than 10 rats each morning, despite a mysterious lull for a few months two years ago.

Traps cannot even be placed in the virtually inaccessible caves and tunnels that pock the island’s 300-foot cliffs. And, from April to August, trapping must end on much of the island to avoid disturbing thousands of nesting gulls.

Even if every rat on the island disappeared, more rats may be able to simply wade over at low tide from nearby Middle Anacapa Island, Ugolini acknowledges.

Some experts question the effectiveness of conventional rat-extermination methods in a place like East Anacapa. “Poisoning and trapping just creates room for one more to grow up,” says David Davis, an ecologist who has helped reduce vast rat populations in San Antonio, Baltimore and elsewhere. “It creates a vacancy.”

Davis, who is now retired in Santa Barbara, has been consulted by the Park Service about the East Anacapa problem. He says only a dramatic alteration of rat habitat can wipe out rats. At the same time, he acknowledges that the Park Service cannot very well burn the shrubbery or seal off the caves on an island it is pledged to protect.

An ‘Unhappy Home’

“But you’ve got to make their home an unhappy one,” he contends. “There are only a very few small areas where you can kill every rat, and the island certainly isn’t one of them.”

Other experts disagree. “The odds are quite good that extermination can be achieved on East Anacapa,” says Rex Marsh, a rodent-control researcher at the University of California, Davis. “This is not an island with luscious tropical growth; it’s not highly satisfactory rat habitat to begin with.”

Such optimism keeps Ugolini going. “On this little island, at least there’s the chance of success,” he says. “That’s what I’ve been thinking for 3 1/2 years, anyway.”

His patience is wearing. He has shied away from the sort of slow-acting poison recommended in 1979 by Santa Barbara Museum of Natural History scientists, but is now willing to give it a shot. He says he is being forced into it by the drain on staff time, the expense of frequent boat trips, and the trails the trapping effort is carving into the brush.

Ugolini will seek permission this month from Park Service officials in San Francisco and from the U.S. Fish and Wildlife Service to lay paraffin cakes containing anti-coagulant poison, which keeps rats’ blood from clotting, in boxes all over the island. Rats nibbling the cakes six or seven times will be just strong enough to stagger back to their burrows and die of internal bleeding, presumably out of reach of the red-tailed hawks and barn owls that prey on them.

Bigger Risks

But the heavier artillery packs bigger risks. Although researchers have noticed no sickness in owls that were fed mice dosed with certain anti-coagulants, other birds also eat rats, and might keep an especially keen eye out for weakened ones.

In addition, two endangered species--the California brown pelican and the peregrine falcon--abound in the Channel Islands. Whereas the pelican eats fish and the falcon swoops on other birds in flight, Ugolini still worries about what might happen if one should vary its menu and include a potentially toxic rat.

If the anti-coagulants are properly applied, the hazards to other species should be minimal, says Marsh, who says such poisons are at the core of 95% of the rodent-control efforts in the United States. “They can be used with relatively little danger to non-target species,” he says.

If the rats on East Anacapa flourish anyway, Ugolini will be stumped. He has been asked more than once whether he has considered setting loose a few good cats, and, in fact, he has.

“But cats,” he says with a sigh, “will destroy the sea birds. And they can be as nasty to get rid of as anything else.”