An elusive fox has been captured after somehow sneaking past a Victorian island's predator defence system, threatening its world-famous penguin colony.
Phillip Island was declared fox-free in 2017 after a 25-year effort to drive them out of the area, southeast of Melbourne.
After several chickens were killed on a local property in early May, animal tracks and droppings were found before infrared surveillance cameras captured a photo of a fox.
Phillip Island Nature Parks on Wednesday confirmed the fox was captured on the island's southern coastline after a two-month operation and humanely euthanised.
It was tracked to the location with the assistance of a conservation detection dog.
How the fox arrived on Phillip Island remains a mystery, with no sign of it crossing from the mainland through cameras operating on the San Remo bridge.
One theory is it may have swam onto the island, with foxes known to paddle significant distances in search of new territory and food.
The conservation team set traps, ran night-time surveys and did detection dog searches to track down the fox, while the droppings and other samples underwent genotyping to determine its sex and obtain a DNA profile.
Foxes are the primary threat to the island's little penguins - the largest colony in the world - as well as other native species, livestock and domestic pets.
"We will continue to remain vigilant and conduct extensive surveys until we are certain that the island is fox free again," acting Phillip Island Nature Parks chief executive Peta Wittig said.
