Complex effort to rid San Nicolas Island of cats declared a success
The problem was daunting: Round up every last one of the who-knows-how-many cats living in the wild on wind-blasted San Nicolas Island, a 33-square-mile chunk of chaparral and jagged canyons off the Southern California coast.
And don’t get in the way of the missiles that are launched from, and sometimes aimed at, the arid, Navy-owned island. And don’t hurt the cats, the seabirds they feast on, the threatened island foxes, the native deer mice or, for that matter, anything else.
The solution was something a little more complicated than “Here, kitty kitty.”
The effort involved six agencies, cost more than $3 million and entailed 18 months of trapping, though planning for it took much longer. Biologists brought in dogs, but soon shipped them out: Fido couldn’t find Fluffy because he was too distracted by the island’s hundreds of foxes. And the cats weren’t falling for the scientists’ “felid-attracting phonics” — digitally recorded meows that didn’t work as well as they might in cartoons.
Ultimately, the job required the skills of a retired bobcat hunter as well as some 250 custom-built traps that flashed computer alerts to researchers miles away. Much of the funding came from the Montrose Settlements Restoration Program, a group formed in 2001 to aid the recovery of coastal areas hurt by decades of DDT dumping.
Earlier this month, biologists and Navy personnel gathered on the rain-swept island to celebrate their success. There wasn’t a cat in sight.
“At first we didn’t even know whether it was feasible,” said Chad Hanson, leader of the effort for Island Conservation, a nonprofit that eradicates invasive species on islands around the world. “It took us quite a while to be able to look someone in the face and say it could be done.”
Hanson, 28, was Island Conservation’s project manager. A biologist who lives near Portland, Ore., he has helped remove goats from an island in the Galapagos and cats from Ecuador’s Isla de la Plata.
San Nicolas had its own challenges, but a professional tracker named Bill Wood could read the terrain well enough to place traps scented with catnip, urine and excrement at just the right spots.
“He could predict just where cats would step and where they would sniff, how long their gait would be and where they’d stop,” Hanson said.
Wood hiked the canyons and ridgelines, creating subtle cat trails with rocks and other obstacles. Weeks or even months after a trap was placed, a curious cat would follow the trail and set its paw on a sensor the size of a half-dollar, triggering a padded jaw that wrapped around its leg, and sending a message about the capture to Hanson’s computers.
There were plenty of unanticipated problems. Crew members had to clear their radio channels with the Navy, Hanson said, “so we didn’t accidentally set off munitions.” They had to avoid disturbing the island’s hundreds of Native American burial sites and midden heaps, consulting a Navy archaeologist before driving to far-flung traps.
San Nicolas is rich in history. It is best known as the setting of “Island of the Blue Dolphins,” a novel based on an Indian woman who lived in solitude there for 18 years. Scholars debate the details of her life, but millions of California students have come to know her as “the lone woman of San Nicolas.”
In 2009 and 2010, planes ferried 59 cats, unharmed, from San Nicolas — where they were examined in a trailer clinic set up by the Institute for Wildlife Studies — to a shelter built specially for them by the Humane Society of the United States in Ramona, near San Diego.
Over the following year, scientists scoured the island 61 miles off Point Mugu for any wily lingerers. Meanwhile, volunteers at the Fund for Animals Wildlife Center in Ramona worked to acclimate the formerly feral critters to humans. Most will be put up for adoption over the next few months.
Cats had roamed the island since at least 1952, probably the descendants of pets brought to the remote base by sailors or civilian employees. From time to time, the Navy tried to get rid of them but failed.
“The techniques weren’t very refined,” said Grace Smith, a longtime Navy biologist. “We could never get to the point of knowing we had the last one.”
Like many military bases, the island is a haven for wildlife.
In breeding season, 2-ton elephant seals bellow on the beach, raising spumes of sand with a whack of their flippers. Island foxes skitter beside massive golf-ball-like structures packed with instruments that collect and relay military data. Blazing with yellow blooms, giant coreopsis plants sit on a bluff above a shoreline where unarmed missiles slam into targets of stacked, rusty shipping containers.
Even with rockets roaring overhead, it was a great place to be a cat — but not so great for the colonies of Brandt’s cormorants and Western gulls that they ravaged. The cats also dined on the federally threatened island night lizard and competed for food with the island fox, a protected species unique to the Channel Islands whose population was rapidly dwindling before the start of aggressive protection programs in the 1990s.
By June 2010, there were no cats left, as far as anyone could tell. But proving an absence of cats is a riddle worthy of a Zen master.
Cat sightings used to be commonplace around “Nictown” — the squat group of buildings where as many as 200 sailors and scientists bunk during the week. But from the galley to the fitness center to the little store that sold such island staples as sweatshirts, booze and canned chili, there were no more reports.
Hanson and his crew pored over thousands of photos from the 54 motion-activated, infrared cameras they installed around the island. They hunted for droppings and bird carcasses. They also relied on the statistical savvy of mathematicians in New Zealand, who developed elegant probability formulas from mountains of data on sightings and scat.
To their relief, they found nothing.
At their recent celebration in a chilly auditorium on the island, officials declared the mission accomplished. Capt. James McHugh, then the commanding officer of Naval Base Ventura County, commended the group for its “monumental achievement.” The scientists and the Navy personnel stopped short of references to St. Patrick and the snakes of Ireland but proudly noted that San Nicolas is the largest island anywhere to remove feral cats without using poison.
The bird colonies appear to be bouncing back. There’s talk of eventually getting the island night lizard off the endangered list. Hanson is preparing to deal with rats on Wake Island. McHugh, who retired Friday, offered a wry wish to the crowd:
“Hopefully,” he said,” if there’s a cat left on San Nicolas, there’s only one.”
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