A Restored 'Jewel'

Located about 12 miles off the coast of Southern California is Anacapa Island, a 700-acre chain of impressive landmasses deemed the "jewel of the Channel Islands" by nature lovers throughout the world. And since the eradication of black rats from the island, this "jewel" has been gleaming a bit brighter.

A non-native species of black rats is believed to have arrived on the island sometime between the mid-1800s to early 1900s on supplies from the U.S. mainland. (One theory is they arrived when the Winfield Scott steamer — which was sailing from San Francisco to Panama — crashed along the island’s shore.) This rodent infestation would become a serious threat to local wildlife.

But after December 2001, that all changed.

Because the black rats were lowering the native sea bird populations to dangerously low levels — the Xantus murrelet and the ashy storm petrel birds were creeping close to extinction — scientists realized something needed to be done.

A NOVEL APPROACH. Bell Laboratories, located in Madison, Wis., worked side-by-side with the Channel Islands National Park to fix the problem. Their solution, although controversial to some, was to treat about 10 acres of Anacapa Island with rodenticides.

While many in the environmental community contested this action, scientists and pest management professionals agreed the benefits far outweighed the costs of rat eradication. "Invasive rodents are responsible for food crop losses and structural damages costing billions of dollars annually," said Peter Martin, technical director of Bell Laboratories. Martin was actively involved in the Anacapa Island project. "Rodent predation caused a serious decline in the sea bird population, placing the impacted species in endangered status that, without intervention, would have resulted in extinction."

Martin said this project was necessary because it allowed declining sea bird populations to escape extinction in order for future generations of visitors to enjoy them.

INHERENT CHALLENGES. While proposing the idea of using rodenticides on the island, researchers came across a few potential problems that could have foiled their plan. Because Anacapa Island has such a steep and rugged landscape, the possibility of the rodenticide pellets actually staying on the island caused some concern.

Researchers also worried that the rodent population would rebound if 100 percent control was not achieved. Because rats can produce up to 5,000 offspring in one year, just one pair of rats failing to succumb to the bait would undermine the entire control effort.

Martin said another concern was whether or not the bait would adversely affect other animal life on the island. "Anacapa Island is home to a number of bird species," Martin said. "In order to prevent accidental ingestion of the bait by these birds, Bell worked with the scientists on the island to develop bait that contained a colorant that did not attract the attention of these birds," allaying the fears of some in the environmental community.

AN ‘AERIAL ASSAULT.’ Following months of meticulous research and thorough planning, an "aerial assault" of Anacapa Island with 9,700 pounds of rodenticide was conducted on Dec. 5, 2001. The ultimate goal was to eradicate black rats from the entire island, a daunting task for even the most seasoned pest management professionals. But Steve Levy, president and CEO of Bell Laboratories, said the outcome was never in doubt, given the level of cooperation between the pest control industry and the scientific community, as well as the extent of the research conducted prior to the actual treatment.

"All formula changes were carefully tested for palatability and effectiveness in the controlled environment at Bell’s in-house laboratory before being subjected to small-scale testing by scientists on Anacapa Island," Levy said.

THE BIRDS ARE BACK. Within a year of the broad-scale rodenticide treatment, sea bird populations steadily began to grow, an obvious sign the absence of rats allowed the birds to repopulate the area without the unique eradication program negatively impacting the environment, an important message for the public, said Valera Jessee, executive director of UPF&DA, an industry trade group. "I think it’s had a positive effect on (the image of) our industry in that people aren’t as dogmatic about the use of pesticides when they’re needed," she said. "They are more realistic, particularly in the case of Anacapa Island" because they’ve witnessed the benefits of pesticide use in preserving nature. "They now know we are the ones who can help in protecting wildlife."

"Projects like Anacapa Island and ongoing work on numerous other locales illustrate that rodent control products — when used with sufficient care and in strict accordance with established management practices — are a safe, effective solution to the problems presented by rodent populations," Levy added. "In the last two years, no rats have been found on the island. In that same period, the indigenous mouse population has been successfully re-established and a significant increase in the migrating seabird population has been documented."

The author is a contributing writer to PCT magazine. She can be reached at jwagner@giemedia.com.