When invasive rats are removed from islands, the ecological benefits can ripple across both land and sea more quickly than scientists expected, according to recent research. Scientists have long assumed that meaningful recovery after the predators are eradicated would take decades. However, researchers with the U.S.-based NGO Island Conservation conducted a rat-removal experiment on Ulong Island in Palau, which provides the first experimental evidence that ecosystems can rebound far more quickly than previously expected. Until recently, rats, which are typically nocturnal, were so abundant on Ulong Island that they were regularly seen during the day. They were a nuisance to campers and deadly for wildlife. As opportunistic omnivores, rats readily prey upon seabird eggs and chicks, devastating nesting colonies on tropical islands. As a result, there were “very few nesting seabirds that we would find,” Coral Wolf, the conservation science program manager at Island Conservation, told Mongabay in a video call. To measure the effects of rat eradication, Wolf designed an experiment in which all the rats were removed from Ulong, while the rats on nearby Ngeruktabel Island remained, serving as a control site. Before the eradication, researchers collected baseline biodiversity data. On land, they recorded bird calls and took soil samples. In the surrounding water, they measured indicators like fish biomass and coral cover. One year after rats were removed, the team repeated the survey and found a dramatic improvement in the biodiversity. Freed from rat predation, seabird activity on the island surged. Detections of bridled tern (Onychoprion anaethetus) calls rose by…This article was originally published on Mongabay

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