As cavity nesters, the birds are easy pickings for the tree-bound snakes. Historically widespread, in 2016 fewer than 1,000 Sali survived on Guam. “This means it’s the best candidate for restoring ecosystem function.” “It’s probably the most effective fruit disperser of the birds that used to be here,” Rogers says. Known locally as Sali, it’s a glossy black bird with a yellow eye and a clear song. (Some are up to four times likelier to germinate after passing through a bird’s gut.) Rogers found that because of the snakes, the number of seedlings for two common species plummeted by as much as 92 percent, thinning once dense canopies.Įnter the Micronesian Starling. Seventy percent of tree species, including the berry-packed åplokhateng and åhgao, rely on birds to gorge on their fruits and spread the seeds far and wide. The density of cobwebs can be up to 40 times greater on birdier isles, hinting that spiders-which compete with avian predators-now overrun the woods. In the absence of birds, Guam’s karst limestone forests, which cover a third of the island, have changed significantly. Iowa State University biologist Haldre Rogers and her team are working to resurrect some of those lost species-and in doing so, help rebuild the larger ecosystem. Others, such as the Guam Rail and Guam Kingfisher, survive only through captive-breeding programs. The 12 forest species were hit especially hard, with only the Island Swiftlet and Micronesian Starling still clinging to existence on the snake-free grounds of a U.S. By the time biologists grasped the problem in the 1980s, snakes had rendered 13 of the island’s 22 breeding birds extinct in the wild, including six endemics. The reptiles, which can grow up to eight feet long and have a native range from Australia to the nearby region of Melanesia, multiplied and ate their way through Guam’s avifauna. military craft from Manus Island in Papua New Guinea. It begins around 1949, when brown tree snakes hitched a ride on U.S. The story behind Guam’s near-silent forests is a classic in the annals of ecological invasion.
If a bold avian reintroduction project is successful, however, the mountainous terrain might once again brim with song.
Ever since birds disappeared a few decades ago, only the hum of insects and rustling of leaves float on the humid air of this 210-square-mile island in the Western Pacific Ocean.