Haldre Rogers, alumna of UW Biology's graduate program and current assistant professor in the ISU Department of Ecology, Evolution and Organismal Biology, studied how the introduction of the invasive brown treesnake to Guam has indirectly impacted forest trees on the island. Rogers’ findings, published this week in the peer-reviewed academic journal Nature Communications, show the potential for invasive predators to cause easily overlooked yet pervasive consequences as a result of extinguishing species that are important for the regeneration of plant species.
The brown treesnake first appeared in Guam, a U.S. territory in the western Pacific Ocean, after World War II. It’s believed the snake may have stowed away on U.S. military cargo ships. The snake, which has no natural predators on the island, quickly drove 10 of the 12 forest bird species in Guam to extinction and drastically reduced the remaining two species. Nearly all the jungles on Guam are silent today, with scarcely a hint of birdsong, Rogers said.
Brown tree snakes, which have wreaked havoc among bird populations on the Pacific island of Guam, may also be damaging the forests. Scientists say that the slithery invaders' dietary habits are preventing the spread of tree seeds by birds. Researchers say the growth of new trees on the island may have fallen by up to 92%. These losses may have grave, long-term consequences for forests and other species.
These dull brown creatures with their bright yellow underbellies are believed to have arrived in the western Pacific island by cargo ship after World War II. Although only 50km long and 10km wide, Guam is now home to around two million of these nocturnal predators. The snakes have thrived on a diet of local bird species. By the 1980s they had wiped out 10 of the 12 forest bird species native to Guam.
"It's a really eerie feeling to spend a day by yourself in the jungle on Guam," said Rogers. "When you're on Saipan, there's this constant bird chatter, and you get visited by different birds. On Guam, it's silent."