Eradicating Black Rats on Palmyra Atoll Uncovers Eye-Opening Indirect Effects
Published:05 Nov.2020 Source:University of California - Santa Barbara
The black rats weren't supposed to be there, on Palmyra Atoll. Likely arriving at the remote Pacific islet network as stowaways with the U.S. Navy during World War II, the rodents, with no natural predators, simply took over. Omnivorous eating machines, they dined on seabird eggs, native crabs and whatever seed and seedling they could find.
When the atoll's managers -- the U.S. Fish and Wildlife Service, The Nature Conservancy and Island Conservation -- were planning to conduct a rat eradication project, UC Santa Barbara community ecologist Hillary Young and her research group saw it as an unusual opportunity. They had already been visiting Palmyra regularly to track another non-native species -- the coconut palm -- to see whether it was spreading invasively in the area, potentially impacting the nesting seabird population and changing the island's soil composition. They had plots where they were monitoring trees in various stages of growth and survival; how would the vegetation respond to the eradication of the island's main seed and seedling eater?