Seabird chicks fall foul of giant centipedes
Petrels are among the unexpectedly varied diet of the very hungry arthropods.
Researchers have found evidence of giant, carnivorous centipedes killing and eating up to 3,700 black-winged petrel chicks annually on a remote South Pacific island. It is believed that this is the first time that such behaviour has been documented.
Phillip Island centipedes ( Cormocephalus coynei) can grow to almost 30cm in length. They subdue their prey by using two pincer-like appendages, called forcipules, to inject a toxic venom into their prey, which, apart from seabird chicks, includes geckos, skinks and crickets.
Despite devouring so many chicks, researchers found that the giant centipedes were not having any long-term negative impacts on petrel numbers, which currently stand at almost 20,000 breeding pairs.
“The population of black-winged petrels is large, so while the centipede predation clearly reduces the reproductive output of the petrels, the centipedes appear only to be able to prey on chicks that are young and small,” said Luke Halpin, one of the researchers.
“Our study found that after reaching a certain age and therefore size, chicks tended not to be preyed on by centipedes. At this population level the black-winged petrel is resilient and appears to be growing with many more petrel chicks surviving to adulthood than chicks that are preyed on,” explained Halpin.
“It’s an entirely natural predator–prey relationship and, in some sense, the centipedes have taken the place of predatory mammals that are absent from the island.”
The giant centipede is now restricted to Philip Island, part of the Norfolk Island group that lies 870 miles (1,400km) off the east coast of Australia, and was only formally described as a species in 1984. At the time, it was thought to be very rare, due to the impact of feral pigs, goats and rabbits on its habitat, after their introduction in the 18th century,
Following the eradication of these animals, black-winged petrels began breeding on Philip Island and have become the most common of the 13 species of seabirds now present.
The population of giant centipedes has since recovered thanks to an abundant food supply (the petrel chicks), though their precise number remains unknown. Simon Birch
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The American Naturalist: journals.uchicago.edu/doi/10.1086/715702