A non-native snake wiped out most of Guam's forest birds, causing a seedling deficit of up to 92% in native trees, with no clear solution in sight.
Guam's forest birds nearly gone
Twelve forest bird species lived on Guam before World War II, but ten have vanished, and the remaining two are functionally extinct, meaning they are so rare they no longer contribute to the ecosystem.Invasive snake caused the decline
The main cause is the brown tree snake, Boiga irregularis, which arrived in the mid-1940s, likely hidden in military freight. Guam had no native snakes before this, and the new predator became the top of the food chain.Seed dispersal suffers
With the loss of birds, the trees of Guam can no longer disperse their seeds effectively. Birds were essential for this task, and their absence has led to a significant drop in seedlings for some tree species.Research on seed traps
To study the impact, Haldre Rogers installed 119 seed traps around artificial trees on Guam and the nearby island of Saipan, which has no brown snakes. Seeds were found only under the canopy on Guam, unlike on Saipan where they spread further.Seeds face higher risks
On Guam, seeds that remain under the parent tree face a higher risk of being eaten by predators or destroyed by fungi. Birds helped move seeds away from these dangers, and their absence has led to a 61 to 92 percent drop in seedling recruitment for some species.Snake's diet has changed
Studies show that the brown tree snake now mainly eats lizards rather than birds, but the damage to the ecosystem continues. The snake's presence has caused power outages, damage to the power grid, and threats to children and pets.Efforts to control the snake
Efforts to control the snake are ongoing, including toxin applications in a 55-hectare area and inspections of outgoing freight. Despite these efforts, eradicating the snake across the entire island is not currently feasible.Restoration efforts underway
The Guam Department of Agriculture is raising birds in captivity to reintroduce them to nearby islands like Rota, where there are no snakes. However, a recent discovery of brown snakes on Cocos Island, near Guam, highlights the ongoing risk of the snake spreading further.
