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Courtesy of Nash Turley, University of Washington
Can Forests Survive Without Birds?
News story originally written on January 30, 2009
Taking one type of animal out of an ecosystem could cause lots of changes. This is what is happening in forests on island of Guam, an island in the western Pacific.
There used to be birds on Guam. But snakes were brought to the island more than 60 years ago and they have been eating the birds. Today there are very few birds left in the forests and there are lots of snakes.
Birds move seeds around a forest. They eat the fruit from a tree swallowing the seeds, and then fly to another tree in the forest where they defecate the seeds. Scientists have been studying how seeds are spread through the forest without birds.
The scientists set traps to catch falling seeds to see how far seeds get from the trees where they formed. They also set up seed traps in the forests of Saipan, an island that still has birds. They counted the number of seeds that fell into each trap. And they compared how far seeds travel in the two places.
So far they have found that seeds on Guam stayed near the tree where they formed while many of the seeds on Saipan were far away from the tree where they formed. It looks like the lack of birds is having an effect.
On the bird-less island of Guam, seeds don’t get moved around. The fruits don’t fall far from their trees. And seeds that are under the tree where they formed are less likely to grow into a new fruit tree than seeds that are moved away from their parent trees.