Hungry Foxes Transform Islands

The introduction of foxes to the Aleutian islands has kicked off an ecological domino effect, scientists said last week. The creatures are transforming the islands from grasslands to tundra. The change has a long history.

After the collapse of the maritime fur trade in the late 19th and early 20th centuries, foxes were imported to more than 400 Alaskan islands as an additional fur source. Some islands remained fox-free, however.

The foxes have preyed on native seabirds, reducing the amount of nutrient-rich guano produced by the birds. The change in soil fertility brought about major changes in the plant community. Donald Croll and colleagues compared seven islands with foxes and seven islands without them and reported their results in the March 25 issue of the journal Science.

Researchers have debated how far the effects of top predators ripple through ecosystems. The new findings show that so-called "trophic cascades" can indeed reach beyond the immediate food web, according to a statement issued by the journal. They also provide a new example of connectivity between marine and terrestrial ecosystems.

The picture at top shows an introduced arctic fox with, in its mouth, a seabird known as a least auklet, which breeds in the Aleutians.

The image at right shows the damage. Leymus grass-dominated plant communities in the Aleutian Islands, at left, have been transformed to communities dominated by low-lying shrubs (Empetrum) at right due to reduced nutrient inputs.

-- LiveScience Staff

Images: © Science