Invasive Brown Tree Snake Changing Forests In Guam, As Well As Wiping Out Most Bird Species - WP

[hatrack]

One of the most infamous examples of what can happen when a nonnative species is introduced into a new environment involves the brown tree snake -- a voracious, semi-venomous species that in less than 50 years all but destroyed bird life on the northern Pacific island of Guam. Introduced inadvertently from the South Pacific just after World War II, apparently on a cargo ship, the snake has killed off 10 bird species on the island and is in the process of wiping out the remaining two.

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"The brown tree snake has often been used as a textbook example for the negative impacts of invasive species, but after the loss of birds no one has looked at the snake's indirect effects," said Haldre Rogers, a University of Washington doctoral student in biology who presented her findings last week at the Ecological Society of America's annual meeting. Rogers, who first went to Guam in 2002 as part of a U.S. Geological Survey "rapid response team" in a bid to keep the snakes from spreading, said she has studied tree growth on Guam and neighboring islands and has found "amazing" differences.

Without birds, which eat the seeds of certain trees and then spread them in their droppings, those trees are losing out to others that do not depend as much on bird middlemen. The seeds of the trees that relied on birds are now falling mostly near the trunks of the parent trees, where they are more likely to be spoiled by fungus and less likely to grow into healthy trees. The result, Rogers said, will either be the loss of some tree species or the clumping of those trees in isolated patches.

"It seems inevitable that the forest will change and some of the native species will lose out," she said. Birds typically make up a small part of the life of a forest, but they are important not only for spreading seeds but also for pollinating flowers and controlling some insects that feed on plants.

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http://www.washingtonpost.com/wp-dyn/content/article/2008/08/10/AR2008081001798.html

[eppur_se_muova]

1. Not a TEXTbook -- but Quammen's "Song of the Dodo" describes this ...

in considerable detail. A good read for anyone concerned about faunal extinctions.