March 8, 2017 by Marlowe Hood
The venomous brown treesnake can grow up to three metres in length
A non-native snake species that has already wiped out most of Guam's tree-dwelling birds is also decimating the Pacific island's forests, researchers said Wednesday.
Growth of new trees on the US island territory may have dropped by as much as 92 percent due to the snake's presence, they reported in the journal Nature Communications.
The findings show that the devastation wrought worldwide on island wildlife by invasive species—especially snakes, rodents and mosquitoes—may be far greater than previously suspected, the authors warned.
"The full impact of the brown treesnake invasion, and the loss of birds, is still unfolding," said Joshua Tewksbury, a professor at the University of Colorado and senior author of the study.
"But our results clearly suggest that the indirect effects are going to be large, potentially affecting forest composition and structure."
Birds play a critical role by eating and spreading seeds from tropical trees.
Probably arriving on Guam via a cargo ship just after World War II, the venomous, brown treesnake—scientific name Boiga irregularis—hunts at night and can grow up to three metres in length.
By the mid-1980s, the snake had eliminated 10 of 12 forest bird species native to the island, including the Guam kingfisher and the Guam flycatcher.
The flycatcher is now extinct globally.
One doesn't have to be a scientist or a bird watcher to notice that something is awry, said the study's lead author, Haldre Rogers, an ecologist at Iowa State University.
"When you're on Saipan"—a neighbouring island where the treesnakes have so far been held at bay—"there is constant bird chatter," she said.