An estimated fifty rare Southern New Zealand dotterel died last year (2022), with Rakaura Stewart Island feral cats blamed for most of the losses, according to the Department of Conservation (DOC).

Just 126 of the critically endangered Southland birds, who breed on the mountain tops of Rakiura and forage in Awarua Bay, are estimated to now remain.

DOC Senior Ranger Kevin Carter said Rakiura Stewart Island experienced a heavy fruiting (mast) event in 2022.

A feral cat. Photo: DOC

"More forest foods means more rats, and more rats means more feral cats - which spells bad news for vulnerable species like dotterels," he said.

“Rats are the preferred prey for feral cats, however, when rat numbers drop off, feral cats look for alternative prey such as Southern New Zealand dotterel."

"While most of the (Southern Dotterel) deaths were likely due to predation – disease, parasites and natural causes may have played a smaller part too," he said.

“Fortunately, some of the adults were able to successfully breed and raise chicks to fledge, which softened the decline, meaning the population as a whole lost approximately 18 individuals.” 

In response to the decline DOC has set up a permanent Southern New Zealand Dotterel Recovery Team to conduct predator control all year round.

Teams will increase feral cat control in dotterel breeding areas, with new trap lines are being installed this Winter, in preparation for the upcoming breeding season, from October until early January.

Carter said controlling feral cats, as well as white tailed deer, black backed gulls, spur winged plovers and harriers which are also known to threaten nesting birds, was key to reversing the decline. 

“Southern New Zealand dotterels have a life expectancy of about 20 years. Sadly, current data shows around 80 percent will not make it past their 5th year." 

“This is why programmes such as Predator Free Rakiura, which aims to remove possums, rats, feral cats and hedgehogs from the island are so important."

"Our trapping and predator control work can hold the line, but the long-term solution requires landscape scale change,” Carter said.

There were 62 of the critically endangered Southern New Zealand dotterels in 1992. The population bounced back to 290 birds in 2010, but has been in decline ever since.