![\"Guam](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/09\/guam-national-wildlife-refuge-beach-credit-laura-beuregard-wikimedia-commons-cc-by-20.jpg\")
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Guam National Wildlife Refuge beach. Credit: Laura Beuregard<\/a> \/ Wikimedia Commons<\/a> \/ CC BY 2.0<\/a><\/p>\n Guam, a small island in the western Pacific Ocean<\/a>, has become the epicenter of one of the most severe ecological disruptions in recent history. Once known for its vibrant forests and diverse birdlife, the island is now dominated by an unlikely apex predator: the brown tree snake.<\/p>\n These invasive reptiles, introduced after World War II, have multiplied into the millions, fundamentally altering the balance of Guam\u2019s ecosystems.<\/p>\n In the decades since their accidental arrival, likely through military cargo shipments, brown tree snakes have silently spread across the island, feeding aggressively on birds, mammals, other reptiles, and even human food scraps.<\/p>\n The consequences have been devastating. Today, Guam\u2019s forests are eerily quiet, stripped of the birds that once filled the air with sound and kept insect populations in check.<\/p>\n Out of the 12 native bird species once common in Guam\u2019s forests, 10 have disappeared. The two that remain survive only in caves and scattered urban areas, far from their natural habitat. The brown tree snake, a nocturnal and elusive hunter, now reigns over this fragile environment.<\/p>\n Snakes eat everything, even what they can\u2019t swallow<\/p>\n Researchers like Haldre Rogers, an ecologist at Virginia Tech who has studied the island\u2019s ecology for over two decades, have observed the far-reaching consequences firsthand. She recalled attending a gathering on the island where a roasted pig was left unattended.<\/p>\n When guests returned, a brown tree snake had wrapped itself around the meat, tearing off pieces and swallowing them whole. For Rogers, it was a startling yet familiar reminder of the snake\u2019s dominance on the island.<\/p>\n The brown tree snake\u2019s impact on Guam is not limited to the extinction of birds. With few predators remaining, the reptiles have shifted their diets to include small mammals, other reptile species, and even each other.<\/p>\n Brown tree snake. Credit: Pavel Kirillov<\/a> \/ Wikimedia Commons<\/a> \/ CC BY-SA 2.0<\/a><\/p>\n Henry Pollock, executive director of the Southern Plains Land Trust and former researcher in Guam, said the snakes are indiscriminate eaters and have been observed consuming animals nearly their own size.<\/p>\n In response to the avian collapse, a surprising new species has flourished: spiders. With their main predators gone, spider populations in Guam have exploded. Parts of the forest have turned into web-covered landscapes.<\/p>\n Surveys have found the island hosts between 508 million and 733 million spiders, roughly 40 times more than neighboring islands such as Rota, Tinian, and Saipan. These figures only include spiders within two meters (6.6 feet) of the ground, suggesting the actual number is significantly higher.<\/p>\n A web-filled forest, alive with spiders<\/p>\n The abundance of spiders<\/a> is visible throughout the year. In contrast to the seasonal fluctuations seen on other islands, Guam\u2019s spider numbers remain consistently high.<\/p>\n Rogers described the scene as something out of a Halloween movie: dense layers of silk blanketed trees, paths, and open spaces. On hikes, it\u2019s common for the lead person to carry a stick to clear webs or risk being covered in them.<\/p>\n The island\u2019s forests are home to a variety of striking spider species. Banana spiders with golden webs, huntsman spiders as large as a human hand, and tent-web spiders that create vast communal structures known as \u201ccondo webs\u201d all thrive in Guam\u2019s environment.<\/p>\n Banana spider golden silk orb-weaver. Credit: bansheed<\/a> \/ Flickr<\/a> \/ CC BY-NC-SA 2.0<\/a><\/p>\n Rogers noted that these condo webs can extend from the forest floor to the canopy, often housing dozens of spiders in a single structure.<\/p>\n These spiders, known locally in the Chamorro language as s\u00e5nye\u2019ye\u2019, are not the only sign of the forest\u2019s imbalance. The forest itself is beginning to change. With birds gone, many native trees are struggling to reproduce.<\/p>\n Around 70 percent of Guam\u2019s native trees rely on birds to disperse their seeds. Now, fruits fall to the ground and rot, or seeds fail to germinate due to a lack of dispersal or poor growing conditions under parent trees.<\/p>\n The silent collapse of Guam\u2019s forests<\/p>\n This disruption has slowed forest regeneration. In a healthy system, fallen trees create gaps that new plants quickly fill. On Guam, these gaps often remain empty. Rogers compared it to tearing down a building in a city, typically prime real estate, but now left untouched due to the absence of seed-dispersing birds.<\/p>\n The brown tree snake\u2019s predatory behavior has become even more disturbing. In a recent study near Andersen Air Force Base, Rogers and her team tracked young S\u00e5li, a forest starling species that still survives in small numbers.<\/p>\n Using radio transmitters, the team discovered many of the devices inside snake stomachs<\/a>. But even more unsettling were fledglings found dead, coated in snake saliva, but uneaten. In about half of the cases, the birds were too large to swallow. The snakes killed them anyway and moved on.<\/p>\n The brown tree snake is not only ruthless but also highly adaptive. To protect the remaining S\u00e5li, conservationists placed nest boxes on tall metal poles with slippery surfaces, believed to be unclimbable.<\/p>\n![\"Brown](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/09\/brown-tree-snake-credit-pavel-kirillov-wikimedia-commons-cc-by-sa-20.jpg\")
<\/p>\n![\"Banana](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2025\/09\/banana-spider-golden-silk-orb-weaver-credit-bansheed-flickr-cc-by-nc-sa-20.jpg\")
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