When the birds are away, the spiders will play, a recent study in the journal PloS One has found.
A press release describes the forests of the island of Guam, situated in the western Pacific ocean, as “eerily quiet” without the calls of songbirds, but spiders are now silently proliferating in the jungle landscape.
The brown treesnake, Boiga irregularis, an invasive species that was introduced onto the island during World War II, preyed easily upon Guam’s birds and their eggs, which were previously unaccustomed to predation, resulting in the extinction of ten out of the twelve native bird species.
Haldre Rogers of Rice University has discovered that the over thirty-year absence of insectivorous birds on Guam has dramatically increased spider populations in limestone karst forests, a jungle ecosystem where trees grow directly on limestone bedrock.
One of the benefits of studying bird exclusion on Guam is that the entire island has been without birds for a long period of time and so is a study site without the problems that small-scale bird exclusion experiments wrestle with, such as systems not having enough time to reach equilibrium or spiders and their prey migrating in and out of study cages used to keep birds out. Full Article »