Thinking inside box helps birds
When weka began breeding around Kathryn Marshall’s home in Nelson, she got to thinking about what could be done to protect the nests of other native birds.
Two years ago, she noticed the number of weka in her backyard was on the rise. So the Atawhai resident left water out for them to drink while rearing their chicks and watched their numbers increase.
‘‘I realised what a massive difference you could make very quickly if something was a good breeder.’’
It led her to look at helping other birds like the mohua, the small yellow bird featured on the $100 note.
Research revealed mohua were once commonly found across Nelson, but a factor in their decline was the long time they spent on the nest, typically within tree hollows, which meant they were easy prey.
‘‘The eggs get eaten, the chicks get eaten and the females get eaten.’’
Marshall said she had a conversation with her father who suggested that instead of predator proofing an area, how about creating a predator-proof nesting box.
Marshall talked to ornithologist Peter Gaze who said recent University of Canterbury research showed the success of rifleman breeding in nest boxes was five times higher than those in natural nest sites.
Marshall said that was largely because the nesting box had a 2.5 centimetre opening that kept rats and larger predators out.
Gaze said species-specific nest boxes were not commonly used as a management tool in conservation but they could maximise gains during breeding in addition to conventional methods of pest control.
‘‘The difficulty is that there are an awful lot of natural holes out there for the rifleman to choose from and they don’t know that the nest box offers a better option than the natural ones.’’
Marshall worked with members of the Waimea MenzShed to create a design and they had since built more than 70 rifleman nesting boxes.
Of those, 50 had been put up in the Brook Sanctuary halo area, 20 had been given to community group Friends of Flora for use in the Kahurangi National Park and four were being trialled in the Abel Tasman National Park.
After her initial success, Marshall moved onto designing a nest box especially for kakariki.
One of the Waimea Menzshed members discovered North American research that a length of tube cut off at a 49-degree angle to make a nesting box entrance was a successful deterrent for predators.
Natureland Wildlife Trust breed kakariki so Marshall talked to trust director Meg Rutledge about testing the nesting boxes at the wildlife sanctuary.
‘‘It probably took them a little longer to go in the tunnel than into a box with just a hole on the front but that is to be expected,’’ Rutledge said.
They were also able to test if the nesting boxes kept mice out. Despite filling them with food, the mice had been unable to get inside.
The relationship with Natureland led to the next design.
The sanctuary also breeds South Island kaka for release but did not have a specially designed nesting box.
So Marshall approached Wellington wildlife sanctuary Zealandia and asked for its kaka nesting box design and the Waimea Menzshed members had a go at making them up.
The initiative is not-for-profit and keeps Marshall busy when she isn’t working.
‘‘In one year we’ve achieved three product types for Nelson that weren’t being used in this environment.’’
The next on the list is a nesting box for the South Island saddleback, with the end goal being a design for the mohua that started it all.