Te Papa researchers are studying wildlife populations in the field to find out about their diversity and behaviours, distribution and threats, with a programme of research on the shearwaters found nesting in New Zealand. We were privileged to visit Titi Island in the outer Pelorus Sound (Marlborough) for our summer field programme.
Titi Island on Google maps
This January 2012, a team of four headed off from Te Papa in Wellington to study flesh-footed and sooty shearwaters nesting in the Marlborough Sounds. These shearwaters are some of the 80 species of petrels found nesting in New Zealand, the global centre of seabird diversity.
The research project aims to examine biological diversity – both in terms of the genetic diversity and species diversity of birds at small island sites around New Zealand, as well as examining key threats to the populations. Understanding pressures on the populations helps to define why they occur where they do, and why their populations may be changing over time.
The work involved estimating population sizes for the shearwaters, we used a combination of counts of burrow density, examining burrow contents with a specialised scope, to give an accurate picture of the wildlife at the site. At Titi Island in the Marlborough sounds, we found the two shearwater species expected – sooty and flesh-footed shearwaters in numbers, both species were incubating eggs in January, but chicks were starting to hatch by 15 January for sooty shearwaters. This is the only site where these two species nest together in any numbers in New Zealand. The larger sooty shearwaters (c.800 – 1000g) dominated, at a ratio of around 1:15 over the smaller flesh-footed shearwaters (c. 600-750g). Other seabirds present were fluttering shearwaters, diving petrels, little penguins and spotted shags.
We scoped over 500 burrows to provide a robust estimate of the occupants of the burrows. The miniaturised camera on a long tube allows researchers to see what the contents of the nest are, including if birds are banded, have an egg or chick, and the species present, with minimal disturbance.
Titi island, like many of the small offshore sites around New Zealand is a haven for wildlife. Wellington tree weta, yellow-crowned kakariki and tuatara were some of the other occupants of this island arc. Some burrows contained both tuataras and shearwaters, who appear to live harmoniously together in the same lodgings.
Our work at the site will continue later in 2012, when we aim to deploy GPS loggers in the shearwaters to define their main areas of feeding, and how they use the marine environment.