Islands With Rats Lose Their Birds

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It may be the year of the rat but the Aleutian Islands is working on evicting the vermin. The action is taking place because of the massive ecosystems that have been changed with the presence of the rodents.

A study out by the University of California, Santa Cruz discovered that not only are introduced rats on Rat Island thriving they have drastically changed the habitat of most of the ecosystem. birds have vanished and so has seaweed. With the change of the seaweed comes more snails, barnacles and other invertebrates.

“When you’re on an island with rats, there are so few birds it’s silent, in contrast to the cacophony on the islands without rats,” graduate student Carolyn Kurle who lead the study said.

With the birds gone the islands see an increase of snails, limpets and other grazers. Those creatures eat more algae and clearing more space for other invertebrates to settle down. The end result is a shoreline stripped of the usual cover of seaweed.

The rat eradication program is expected to begin this summer.

Kurle spent three summers doing intertidal surveys on 32 islands. 17 had rats while the other 15 were free of the rodents. On islands that had rats the nighttime activity was almost deafening. The rodents seem to be everywhere. With that many rats the birds fall victim to their appetite. Rats mainly attack the young birds but if hungry enough will go after the adults. In the end bird breeding is almost impossible to do on an island with rats.

Another study completed by Donald Croll and assistant adjunct professor Bernie Tershy of UCSC’s Department of Ecology and Evolutionary Biology shows the direct results of rats and seabirds. Published this February in Conservation Biology the paper reviews a total of 94 published studies.

There is good news. Rat eradication has taken place on 274 islands throughout the world. Once the rats are removed the ecosystem rights itself.

“It’s been done many times,” Croll said. “What’s interesting is the synergy between the research and the conservation efforts. Academic researchers tend to do studies and publish them, and then nothing happens. So it’s very exciting for our students to see that their research can tie in directly with the conservation mission of a large organization like the Nature Conservancy.”

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