Spider Population Explodes in Guam - as part of the news series by GeoBeats.
The exploding spider population in Guam is reaching numbers up to 40 times higher than nearby islands. This is due to an invasive species of snakes that entered Guam from their native Australia in the 1940’s. Their diet consists mainly of birds and by the 1980’s the snakes had already killed off ten of twelve native species of birds.
The loss of birds on Guam resulted in spider populations having a larger food supply and fewer predators, which in turn caused their numbers to grow quickly.
The number of spiders in the forests of Guam was compared with the nearby Marianas Islands, which are not subject to a brown tree snake invasion.
Researchers studying the growing spider populations in Guam and the correlation with decreasing bird populations think that there may be a similar situation in other places,
The lead author of the study noted: “With insectivorous birds in decline in many places in the world, I suspect there has been a concurrent increase in spiders."
