Rabbits and penguins

Gentoo penguin chicks with one of Macquarie Island's rabbits. The Gentoos are native to the island, but rabbits certainly are not. So what is the story? (Sorry it's so long!)

Very briefly, rabbits were introduced in 1879 by a sealing company as a food source for their sealing gangs (at that stage busily killing elephant seals for oil). The number of rabbits bred rapidly, as rabbits do, and they shortly covered the island. Cats had been introduced as early as the 1820s at which time they would have been predating the ground dwelling birds, but when the rabbits arrived those also would have provided a good food source. It seems the numbers of rabbits increased and decreased at different times over the years, but there was a tenuous balance between cats and rabbits.

When I lived on the island in 1968, rabbits were plentiful on the main part of the island but not near the station or on North Head. We often shot them as a food source. There were a relatively few cats. But the rabbits were seen as the main problem because of the damage they caused to vegetation and the resulting erosion. During my stay, workers from the Tasmanian Environment Department began efforts to introduce the rabbit flea as a vector to transmit the myxomatosis virus, as used in Australia (the usual insect vector species could not survive the climate). Some years later there was success and the rabbit numbers declined dramatically. At that point, someone became over-excited in the Tasmanian Parks Department and a decision was made to eliminate the feral cats on the island as they would attack the bird life.

A substantial hunting campaign was begun in 1998 and the cats were all killed by 2000. There proved to be only a little over 1000 on the entire island. But .... by then the rabbits had developed an immunity to myxomatosis. Within a few years, in the absence of predators, their numbers had ballooned far in excess of what they ever had been. Everyone on the Marina Svetaeva in 2005 was horrified at the damage they were causing, particularly those of us who had lived on the island and knew how it previously looked. What was worse, they were everywhere including areas they had not infested years before. At that time, there was a proposal under development to begin a massive programme to eliminate rabbits (also rats and mice), using helicopter-dropped baits, to be followed by intensive hunting for any survivors. Most of us had reservations, based on the likely effect on the scavenging seabirds, but something had to be done.

Finally the details were worked out, Government funding approved, and the work began in 2010. That first year of the baiting programme had to be abandoned due to weather, but it resumed in 2011 and I am glad to say that no live rabbits have been seen on the island since November of that year. Hunting and tracking teams, with sniffer dogs, have been constantly patrolling the island since the baiting and I gather will continue doing so until 2016. And I understand the vegetation is now thriving again.

UPDATE: It is now over two years since any rabbits, rats or mice were last found on the island.