Predator Deadpool 2018: What's on the list…

Feral cats, hedgehogs, ferrets. They may look cute and fluffy, but they are among a number of predators killing the Waiau Toa/Clarence river black-fronted terns.

Black-fronted terns are ranked Nationally Endangered and have a predicted decline rate of around 50 percent over the next 30 years if no action is taken to protect them.

A 2012-14 Department of Conservation and Wildlife Management International Ltd study of the upper Waiau Toa/Clarence and Acheron Rivers black-fronted tern breeding colonies showed survival rates were extremely low due to predation by introduced mammals.

Five-year predator control project

As a result, the Kaikōura Water Zone Committee, DOC and Environment Canterbury committed more than $500,000 to a five-year predator control project.

The project involves predator trapping around three main breeding colonies and is supplemented by weed control and habitat enhancement.

During the 2017/18 black-fronted tern breeding season, a total of 492 predators were caught, with hedgehogs making up almost half of that total.

According to DOC, hedgehogs are a major predator on eggs of braided river birds such as the black-fronted tern and are known to kill and eat chicks of a variety of ground-nesting birds.

However, while hedgehogs were the most commonly caught predator, feral cats continued to prove they were the most dangerous predator to the Waiau Toa/Clarence River black-fronted tern colonies accounting for 17 percent of observed nest failures in the 2017/18 breeding season. 

Australasian Harriers 

Australasian Harriers are included specifically in the Waiau Toa/Clarence River predator control programme as monitoring and surveillance of the Waiau Toa/Clarence River black-fronted tern colonies showed harriers were a major predator of these Nationally Endangered birds. 

Australasian harriers are having the same impact on the Waiau Toa/Clarence River black-fronted tern colonies as mammalian predators such as rats, stoats and ferrets. 

The project does not seek to eliminate Australasian Harriers, but rather reduce their numbers around the three colonies of Nationally Endangered black-fronted terns included in this project in order to give them a better chance at survival. 

However it is important to note that Australasian Harriers are partially protected under law and may only be killed for reasons stated in the Wildlife Act 1953 [as per the Wildlife (Australasian Harrier) Notice 2012], and there are strict instructions on what should happen should an Australasian Harrier be killed. Killing Australasian Harriers under any other circumstance is illegal.

Black-fronted terns are ranked Nationally Endangered and the greatest decline in tern breeding populations has been on rivers classed as 'low-flow' such as the Waiau Toa/Clarence River. 

Read more about the Black-fronted tern five-year protection programme here.

The good news…

The combination of predator trapping, weed control and habitat enhancement is having a positive impact on the Waiau Toa/Clarence River black-fronted tern population.

When the project began in 2015/16 only one egg per 10 nests survived to fledgling stage.

This year, one egg per two nests survived.

The project will continue until 2020.

Read more about the Black-fronted tern five-year protection programme here.