Thriving weka numbers on Kapiti Island have been causing a problem for some of the other island residents, particularly our native tītī/sooty shearwaters.
The problem
Kapiti Island has been free from mammalian predators for over 20 years and is a haven for native wildlife. It’s home to a variety of rare and endangered species including little spotted kiwi, kōkako, tīeke and hihi. These native birds thrive in this natural environment.
Kapiti Island
The weka on the island – now hybrids of at least two varieties introduced in the 1890’s – have also been doing extremely well in the absence of mammalian predators, but unfortunately their numbers are proving to be problematic for some of our other native species.
Weka
Scientists advised that a remnant tītī/sooty shearwater colony near the island’s wild western cliff tops were under pressure from the weka, which were preying upon their eggs and young chicks.
Tītī in a burrow
The solution
The idea was born to construct fences, to stop weka accessing the burrows of the tītī colony, on the island’s western cliffs. The fences were built last year, and were a joint venture between the US Embassy, DOC, iwi and volunteers.
Constructing the weka exclusion fence
The exclusion fences will help to keep weka out of important breeding habitat for tītī. Departure ramps were included in the construction to allow tītī to safely launch back out to sea from their breeding grounds.
The finished weka exclusion fence
Tītī numbers across New Zealand are declining, so keeping weka out of their important breeding grounds will give them a fighting chance at recovery. Historically, tītī would have been abundant on Kapiti and an important food source for Māori and early whalers. Seabirds benefit the ecology of offshore islands by bringing nutrients ashore.
The results
Tītī have successfully found their way into the weka exclusion areas on Kapiti Island and they have now been spotted being able to navigate the departure ramps too. This is fantastic stuff and a long time in the making.
Tītī successfully using the departure ramps
Motion sensor cameras will also tell us if any cunning weka have found any weak spots along the fence line.
The next steps are to install some small one-way tunnels along the fence line, to give juvenile birds an extra exit route when they fledge. Night surveys of the colony in the New Year will hopefully prove more tītī chicks get that chance this breeding season.
“Our challenges with weka on Kapiti are pretty unique and this solution was quite experimental – but guided by expert science advice. It’s exciting to see positive signs that all the hard work might pay off,”
– Kapiti Island Ranger Nick Fisentzidis.
Working with the US Embassy
The US Embassy has supported a number of conservation activities recently as part of the 100-year anniversary of the US National Parks service. This included releasing a kiwi into Rimutaka Forest Park, supporting education visits, and sponsoring interpretation panels about nature and history on Kapiti Island.
New interpretation panels on Kapiti Island
Their support showcases our shared values around the importance of nature in people’s wellbeing. Thanks to the US Embassy, iwi and other volunteers for all their help and support on this project.
