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Norway rats
stowed away on ships of all types and sizes.
Pictured here is the mail packet, the Dora, which
made routine runs from the mainland to the Aleutian
Islands. |
For centuries, most islands in the Aleutian chain and in the Bering Sea had few terrestrial mammals besides humans. In the absence of predators, bird populations flourished in ideal ground nesting and feeding conditions. But in 1828, Norway rats traveling (uninvited) on Russian ships, began to infest Alaskan islands, and infestation increased steadily. In the early 1940s hundreds of U.S. military ships routinely visited the Aleutians, and the rat infestation grew ever more serious.
The natural characteristics of the Norway rat account for much of the problem. It has been an opportunistic sea traveler for centuries. It is an incredibly adaptable species, surviving and flourishing anywhere humans do. With good eyesight, keen hearing and a sharp sense of smell, these small mammals adapt quickly to the harbors and rocky coasts of the Alaskan Islands, where nesting birds, eggs, and hatchlings provide an excellent source of food. Rats are agile, curious, and amazingly prolific breeders. They are short-lived (their life expectancy is about a year), but they are productive. A single female will have up to forty nestlings in a year. They are also destructive. In the 1950s rats devastated the bird population of the Queen Charlotte Islands. Two types of auklet and two types of petrels entirely disappeared from the locale. Tufted puffins, which had numbered in the hundreds of thousands, are now rarely seen.
A Threat to the Pribilof Islands
It is not only the bird populations that suffer once rats are introduced. David Cormany, who works for the National Marine Fisheries Service on the Pribilof Islands, told film director Larry Hott in 1999 that he regards "the introduction of rats to be worse than an oil spill. A rat infestation could very well introduce diseases to the northern fur seals here, and would certainly decimate the sea bird population. The Pribilof economy is now built largely around seafood processing. And with that seafood processing we get a lot of vessel traffic which brings the threat of rats."
Rat populations are very
difficult to eradicate, which means that if rats do reach
the Pribilofs, they will most likely be there for good. That
is why Pribilof Island officials have established a campaign
to keep rats off their shores. Ships with rats cannot come
within three miles of the harbor; traps and poison have been
set out in St. George and St. Paul at points where the rat
spill is likely to occur. Prevention seems to be the key --
in New Zealand, scientists have successfully gotten rid of
rats on very small islands, but on larger ones they are
simply unable to eradicate the tenacious rodents that
threaten the native species.
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For information on the Harriman Retraced Expedition e-mail: harriman2001@science.smith.edu |