2 weeks Ago
There’s nothing particularly spectacular about the brown tree snake. Its venom is weakly neurotoxic at best; bites aren’t considered to be dangerous for adult humans. Its appearance is quite ordinary, with no impressive ornamentation (like the spider-tailed viper ) or vibrant colors.
And yet, this modest snake is one of the most destructive invasives in the world, directly responsible for the extinction of over a dozen animal species and indirectly responsible for the decline of an entire island ecosystem. The brown tree snake, or Boiga irregularis , is native to Australasia, including New Guinea, its surrounding islands, and the northeastern coast of Australia. It was towards the end of World War II when it was accidentally introduced to the remote Pacific island of Guam—a key military base located over 1,000 miles north of the snake’s native range.
For 20 Years, The Brown Tree Snake Evaded Eyes While Annihilating Several Species The snake is believed to have arrived on Guam in the 1940s as a stowaway in military cargo from the Admiralty Islands in Papua New Guinea. However, people were oblivious of its presence on Guam until 1953, and still unaware of its deadly rapid spread until much later. The brown tree snake was an alien in its new home, free of natural predators.
But being able to consume as much as 70% of its body weight, the snake had a substantial appetite. This tree-dwelling snake was free to prey abundantly on a wide variety of local fauna, which had no defenses in their arsenal against any snakes at all, let alone this unknown predator. In its native habitat, the brown tree snake’s population is naturally regulated by prey species that have evolved defenses against it, as well as by parasites, diseases, and other predators like the red-bellied black snake, which feeds on Boiga irregularis in Australia.
But in Guam, with no predators and an abundance of naive prey, its population exploded. The snake caused the extinction of most of the island’s native breeding birds. Guam’s forests fell silent as 10 of the island's 12 forest-dwelling bird species vanished from the wild.
Two bird species—the Guam kingfisher and Guam rail —that were driven to extinction in the wild were endemic, found nowhere else on Earth. The devastation cascaded across the ecosystem, of which birds were gardeners, playing a critical role in pollination and seed dispersal. With them gone, the island’s vegetation also began suffering.
Not all species went extinct, but the consequences were still dire. The snake’s feeding activities reduced the populations of other birds, native bats (like the tiny Mariana fruit bat) and lizards. They also impacted domestic poultry and pets.
Interestingly, the snake was not only an invader of grassland and forest ecosystems, like the ones it belonged to in the east, but also of power facilities. Devastation Caused By The Brown Tree Snake Even Called For Public Health And Economic Interventions By the 1950s, their populations had grown to such overwhelming numbers that they began to cause frequent power outages. This was owed to their habit of climbing power poles and causing short circuits when they came into contact with electrical equipment.
Between 1978 and 1997, it was estimated that brown tree snakes were responsible for 1,600 outages, costing the island on average $4.5 million every year in repairs and lost productivity. The devastation brought out by the snake left an unmissable mark.
In an effort to protect other Pacific islands from this volatile invasive, the U.S. government began spending millions every year to inspect cargo leaving Guam.
Although the snake is not particularly dangerous to adult humans, in large numbers, it began to turn into a public health concern, and led to human-wildlife conflict. Residents were anxious about venturing into outdoor areas, beginning to fear encounters and potential bites. With brown tree snakes frequently entering homes, children—whose lower body masses could render bites far more dangerous—were now at risk.
Schools and local authorities conducted awareness campaigns about the snakes. To date, the species is still a critical point of concern on the island. Their populations are thought to be in the millions today, with various control strategies over the years having limited success.
The U.S. Fish and Wildlife Service , in partnership with local organizations, attempted several strategies over the years, with an innovative one involving the use of bait laced with acetaminophen, which is toxic to snakes but harmless to birds and mammals.
Efforts to reintroduce some of Guam's extinct species that were preserved in captivity are underway, but only time will tell how successful they’ll be, as the brown tree snake appears to be a permanent presence on the island. If our wild spaces aren’t managed effectively, negative human-animal encounters are inevitable (like with the brown tree snake), leading to aggression, fear or dislike. It’s tough to feel at one with nature in such a case–a disconnection also felt in urban areas where nature has completely been wiped out.
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