The US island ruled by alien snakes and spiders

Guam is a small island located in the western Pacific Ocean, approximately 2,492 kilometers from the Philippines. It is known for its lush green forests and unique wildlife. However, the island is facing a significant ecological crisis due to the introduction of invasive species, particularly the brown tree snake and an overwhelming population of spiders. Five years ago, Haldre Rogers, a scientist who has dedicated over two decades to studying Guam's ecology, attended a gathering on the island. During the event, an unexpected visitor made an appearance. As the evening progressed and the guests mingled, they returned to find a brown tree snake feasting on a roasted pig. This snake, with its shiny scales and wide mouth, was devouring the pig's flesh without any hesitation. The brown tree snake is believed to have arrived on Guam accidentally, likely by hitching a ride on a cargo ship. Before the snake's arrival, Guam was home to a diverse range of native birds that thrived in the island's limestone forests. However, within just a few decades of the snake's introduction, the bird population began to decline dramatically. Out of 12 native bird species, 10 have gone extinct, while the remaining two are struggling to survive. The brown tree snakes have become voracious predators, consuming anything they can find, including human leftovers. They are so desperate for food that they even resort to cannibalism. The absence of birds has left Guam eerily quiet, as the cheerful sounds of chirping and singing have been replaced by silence. The ecological consequences of the snake invasion extend beyond the loss of birdlife. An unexpected beneficiary of this situation has been the spider population. Rogers, who is not afraid of spiders, has observed that Guam's limestone forests are teeming with them. During the rainy season, the number of spiders on Guam far exceeds that of neighboring islands. The forests are adorned with intricate webs, and every step taken reveals more of these silken structures and their eight-legged inhabitants. Some spiders, such as the banana spider, are particularly large and create expansive webs that can be found throughout the island. Rogers refers to certain types of spider webs as 'condo' webs, as they resemble apartment complexes housing numerous spiders. These communal webs are home to many individual spiders, all working together to catch insects. The unique environment of Guam's limestone forests adds to the strangeness of the island. Towering trees, such as breadfruit and cycads, create a dense canopy, while the ground is rocky and challenging to navigate. Rogers has to train new researchers on how to walk in this environment, as the sharp rocks can be difficult to traverse. In 2012, Rogers decided to conduct a survey to determine the spider population on Guam. She and her team carefully walked through the forest, counting the spider webs they encountered. Their findings revealed a staggering number of spiders on the island. During the wet season, Guam had 40 times more spiders than the nearby islands of Rota, Tinian, and Saipan. The webs were also significantly larger, indicating a thriving spider population. The researchers estimated that there could be between 508 and 733 million spiders in Guam's forests, each contributing to the intricate web of life on the island. The absence of birds has allowed the spider population to flourish, as they no longer face predation. The brown tree snakes have disrupted the natural balance of the ecosystem, leading to an explosion of spider numbers. The impact of the brown tree snake invasion has been profound. Although scientists began to notice the decline of bird species in the late 1980s, it took time to identify the cause. Julie Savidge, a researcher at the time, conducted a study to uncover the mystery behind the disappearing birds. Her research revealed that the brown tree snakes were responsible for the decline. The native birds of Guam had no natural defenses against these predators, as there were no native snakes on the island. As a result, the birds became easy prey for the hungry snakes. By the time the true extent of the problem was understood, many bird species were already on the brink of extinction. Some species, like the Guam kingfisher, were thought to be extinct in the wild until recently when a few individuals were discovered in captivity. The brown tree snakes are not only effective hunters but also exhibit remarkable adaptability. They can consume prey much larger than themselves, demonstrating their insatiable appetite. Conservationists are working tirelessly to protect the remaining bird species by providing safe nesting areas, but the snakes have proven to be clever and resourceful. Despite numerous efforts to control the snake population, they continue to pose a significant threat to Guam's wildlife. The forests are undergoing a transformation due to the absence of birds. Many trees rely on birds to disperse their seeds, and without them, the forest is struggling to regenerate. The ecosystem is becoming increasingly unbalanced, and it remains uncertain whether it can recover. For now, the brown tree snakes and the multitude of spiders they have inadvertently allowed to thrive are firmly established on Guam, and their presence may persist for the foreseeable future.