There are no large snakes native to Guam, so the birds, or avifauna, that lived there did not stand a chance against the arboreal predators. In a relatively short time period, the snake spread across the island and wiped out 10 of the 12 species of forest birds, several of which were endemic.
The brown tree snake is a perfect example of how an invasive species can disrupt an entire ecosystem. It has not only wreaked havoc on the birds in Guam but also resulted in the disappearance of six of 11 native lizards and two of three native bat species. The loss of these species has caused cascading effects on the island’s forest ecosystems.
Guam’s birds are like gardeners. As they move through the forest, they disperse the seeds of the fruit and plants they consume. When the birds began disappearing, so did the forest. There is now less diversity in the species of trees that grow, and the forests are thinning. In addition, spider populations have exploded because there are no birds to prey upon the insects. Apart from disrupting Guam’s ecosystem, the brown tree snake has also had significant economic consequences due to its affinity for climbing power lines, which causes frequent power outages on the island.
The effort to save the Guam rail began in the early 1980s when biologists from Guam’s Department of Aquatic and Wildlife Resources captured the last 17 birds to start a breeding and recovery program. One of the first transfers of birds from Guam to the mainland United States occurred in 1985, when 12 birds were brought to the Smithsonian Conservation Biology Institute.