Tiritiri Matangi – Nest checks underway

Spring has sprung on Tiritiri Matangi and the plants and animals are responding. Most notably, many of the kōwhai trees on the road between the wharf and the visitor centre have clusters of bright yellow flowers. Those in flower often have a tūī taking advantage of the source of nectar and vigorously defending their adopted tree against all comers. Kōwhai often have few, if any, leaves at this time of year, but those that do will be visited by kererū/pigeons which will steadily munch their way along the branches stripping them bare of the tiny leaves.

And while the forest birds have yet to begin nesting, some of our seabirds are well underway. On Tiritiri Matangi kororā/little penguins tend to lay their two eggs in August although last year many delayed until October or November, probably because they couldn’t find enough food for the females to produce and lay their eggs.

A mid-August check of our nestboxes found eleven pairs each with two eggs so they are off to a good start. Kuaka/diving petrels lay their single egg in August, but none were found when checked mid-month although there was plenty of evidence of fresh burrow digging so the birds are present. Ōi/grey-faced petrels are our largest flighted seabird (though only half the weight of a kororā which weighs about one kilogram) and they will have laid their single egg back in June or July and already be well into their eight-week incubation period. 

Other seabirds nesting on the island include karoro/black-backed gull, tarāpunga/red-billed gull and tara/white-fronted tern. They are largely absent in August, returning to nest from October onwards. We monitor the nesting numbers and success rates for a sample of birds each year and this time we will be watching anxiously for the potential arrival of bird flu which is currently impacting greater crested terns and other seabird species in Australia and has been detected in Aotearoa in a kāhu/swamp harrier and a hākoakoa/subantarctic skua. It seems highly likely that bird flu will spread to seabirds here.

Experience from the northern hemisphere suggests bird flu will cause high mortality rates in colonially nesting seabirds, waterfowl and birds of prey. There have been lesser impacts on other species. Our concern in Aotearoa is for some of the rarer endemic species like takahē, kākāpō, tūturuatu/shore plover, kakī/black stilt and kākāriki karaka/orange-fronted parakeet which could be brought nearer to extinction by bird flu. The Department of Conservation has a protective inoculation programme for these species.

Spending an overnight on the island is just about the best way to experience the widest possible range of wildlife, but if you can’t manage that, why not try a special ‘dawn chorus’ trip. This year departures are from Auckland at 4am and Gulf Harbour at 4.55am on October 3 and 10. Check out the Explore ferries website for details and bookings.