Aleutian Seabird Restoration Project

Another island rat-eradication project has found its way to Bell Laboratories' door, with additional ones lining up, as Bell's reputation as a manufacturer of a unique brodifacoum bait used to rid islands of seabird-preying rats continues to grow.

This recent project, the Aleutian Seabird Restoration Project, is focused on removing non-native Norway rats from Rat Island, one of the furthest outlying islands in the Aleutian Islands chain in the Alaska Maritime National Wildlife Refuge. Aptly named, Rat Island has been awash with rats since they first found their way to land after a 1780s shipwreck in the north Pacific. Over the years, as rat populations grew, the number of seabirds and seabird species on the island declined.

Rats wiped out the puffins, auklets and storm petrels that would nest in the island's craggy coastline. Adult birds sitting on nests were easy prey for feasting rats who would go after the eggs or young chicks.

Today with dangerously few birds left on Rat Island, collaborative members of the Aleutian Seabird Restoration Project - the U.S. Fish & Wildlife Service, the California-based Island Conservation and Ecology Group, and The Nature Conservancy - hope to reverse that trend by ridding the island of rats. The method of eradication is aerial application of a special brodifacoum bait developed by Bell.

Aerial Drop of Brodifacoum Pellets
In October 2008, a specially equipped helicopter, flown by New Zealand pilots experienced in aerial baiting, broadcast 25 tons of brodifacoum pellets on the 10-square mile Rat Island. A week later, they dropped a second application of equal amount. Working in unexpectedly good weather, the team accomplished in 12 days what they thought would take 45 days.

Staging a project of this magnitude on an island located 1500 miles from Anchorage in the far-off Aleutian chain took a great deal of preparation. With no facilities on Rat Island, every bit of food, fuel, equipment and staging materials had to be shipped in before the air drop. Even the 50 tons of bait that Bell manufactured had to be stored in custom-built wooden boxes with water-tight seals and screened bottoms to keep moisture, insects, and, yes, rodents out.

Bell, the only company in the U.S. to manufacture a successful bait for these projects, developed a hard, bright-green pellet bait, one half-inch in diameter and length, for the Rat Island project.

"The pellets were designed to survive an aerial drop yet not drift off the mark," said Bell's Director of Research and Development, Peter Martin. "The larger size also makes them too large for small birds which significantly reduces the risk of non-target poisoning."

In addition, pellets had to hold up in high humidity conditions. "The bait had to remain palatable for about two weeks but we didn't want the pellets to last forever because of non-target poisoning," Martin stressed. Brodifacoum is a single-feed bait, hence rodents can consume a lethal dose in a short amount of time.

Bell's first involvement in island rat eradication projects came in 2002 when the company developed bait used on Anacapa Island off the coast of California. Since then it has developed bait for similar projects in the tropical Palmyra Atoll in the Pacific.

Monitoring Rat Island for Next Two Years
Several days after the air drop, researchers on the island found dead rats but most of the monitoring will take place over the next two years.

In June, a team of biologists return to Rat Island with monitoring tools, such as traps and chew blocks, to check for rodent activity. They will leave the monitoring tools in place during the winter and will return in the spring of 2010.

"Only after two years of monitoring with no detected rat activity will Rat Island be declared rat-free," noted Dustin Solberg of The Nature Conservancy. "Ultimately the success of the eradication will be determined by beneficial ecosystem changes. Following rat removal, we expect to find significantly improved native habitat and long-term lasting benefits to birds."

If signs of rats are detected, such as droppings or tracks observed, monitoring will continue in 2011. And, while that is going on, Bell will move on to other projects, including one in the Galapagos Island to help eradicate rats that are feeding on the eggs and young of the giant sea tortoise.

Photo credit: Island Conservation