Giant bird-eating centipedes are restoring ecological balance to Phillip Island

On a tiny island in the South Pacific, the Phillip Island centipede or ‘Cormocephalus coynei’ stalks through the undergrowth on humid nights.

Growing up to almost a foot in length the diet of the exclusively nocturnal arthropod varies wildly, using two pincer-like appendages known as ‘forcipules’ to ensnare victims and inject them with venom.

Monash researcher Luke Halpin said the giant centipedes on Phillip Island (not the island in Victoria’s Westernport Bay) can eat up to 3700 black-winged petrel (Pterodroma nigripennis) each year.

“They tend to go for the back of the neck and immobilize them that way using all of their front walking legs to help deliver the venom,” he said.

“The signs that we see on the predated chicks tend to all be the same.

“The centipede has trashed away at areas where there’s a little less downy feathers, so the flesh is more accessible and that tends to be around the back of the head and around the mandible, the jaw or the beak.”

As the researchers carefully observed the eating habits of the centipede, there was an instance where a centipede eating a black-winged petrel nestling was filmed.

New research by Monash University, published in The American Naturalist, finds that ‘nutrient exchanges’ on the island are driven by arthropod eating habits, with the giant centipede consuming anything from geckos to fish to baby birds.

According to the study, the black-winged petrels remain resilient to predation levels, so the centipede is fulfilling the ‘ecological niche’ often filled by predatory mammals.

In this way, nutrients brought from the ocean by seabirds are distributed by hungry centipedes which help to structure the nutrient flows across the island.

But the centipede has not always thrived.

The delicate island ecosystem was ravaged by introduced pigs, goats and rabbits, each destroying the delicate balance between vegetation and endemic species.

WWF International global practice leader Margaret Kinnaird said human-wildlife conflict, like that caused by introduced species, has pushed naturally less abundant species to the brink of extinction.

“Within a human lifetime, we have already seen extraordinary and unparalleled changes to our planet,” she said.

“Global wildlife populations have fallen an average of 68 per cent since 1970.”

In 1988, rabbits were finally exterminated from the island making way for burrowing seabirds in soil that would become the hunting ground for giant centipedes.

“The rabbits obviously burrowed into the ground, and they ate all the vegetation and that has caused desertification,” Mr Halpin said.

“If you look at satellite images of Phillip Island, you’ll see that much of it is red and ochre and orange and those are the areas where the forest, where the vegetation has been completely denuded.

“If you think back 150 years ago the island would have been covered in a subtropical rainforest, lots of endemic species’ palms, [and] lots of other endemic plants.

“Many of those plants are now existing at very low numbers and many are critically endangered and they’re endemic, they’re not found anywhere else.”

Reference: Monash research study titled “Arthropod Predation of Vertebrates Structures Trophic Dynamics in Island Ecosystems” and published in The American Naturalist available: https://www.journals.uchicago.edu/doi/10.1086/715702