Island Biodiversity is the theme for today’s International Day for Biological Diversity.

To celebrate, DOC ranger Tansy Bliss writes about her job protecting the biodiversity on New Zealand’s Chatham Islands…

It’s May and the busy season of species protection work on the islands of Mangere and Rangatira in the Chatham Islands is coming to a close.

Rangatira Island, the third largest island in the Chatham Islands archipelago

It is often hard to find time for quiet reflection, but our final day on Rangatira sums up what is has all been about.

Naomi Muhlbacher holds a Chatham petrel chick

Trainee Ranger, Naomi Muhlbacher, holds a Chatham petrel chick. It lives in an artificial burrow installed in the nineties to help protect one of the rarest seabirds in the world and reduce burrow invasion by broad-billed prions.

With an estimated 300,000 prion pairs on Rangatira, and only 150 known Chatham Petrel pairs, competition for burrows is high.

I am fitting the chick with a metal band, so when it returns to breed in 3-5 years time, its identity can be verified.

This island was farmed up until the late fifties and most of the burrowing seabirds lost their home to heavy footed cattle and wandering sheep. Now the ground is so pitted with burrows, we wear wooden boards on our feet to prevent us damaging them further.

A black robin comes in to take advantage of the loosened soil and insects I have scooped out of the plastic tunnel entrance to ensure the chick has free passage to come in and out when exercising its wings ready for departure over the next few weeks.

Black robin

Chatham Island red-crowned parakeets chatter above us in competition with the Chatham Island tūī, fluttering from tree to tree, with constant vocalisations.

A Chatham Island snipe snuffles through the leaf litter, totally unperturbed by our presence and a male Chatham Island tomtit, sounds his alarm as he wards off the black robin from the fresh feeding ground.

Chatham Island red-crowned parakeet

Last month a team of highly skilled volunteers and I scoured the island searching for black robin—completing the annual banding and post-breeding census.

On an island with almost 200 hectares of potential robin habitat, it is quite a job.

Currently there are 229 known colour-banded adult black robins and 70 juveniles on Rangatira. The nearby island of Mangere is smaller and with less than 10 hectares of mature forest, and holds a population of 45 adults and 9 juveniles. With this being the entire population of black robin in the world, protecting them is high on our priority list.

A young black robin inspects the drop trap looking for a meal worm

Before leaving Rangatira, we recheck all the coastal bait stations for sign of nibbling rodents and ensure all bait is fresh and ready for any unwanted arrivals. The rough seas around the islands and the rat free status of the nearest neighbour, Pitt Island, has probably helped keep the islands pest free. However bio-security is still the most important job I do and the responsibility of getting it right every time feels enormous.

Today, we pause to relax in the sun on the lichen covered rocks with the skinks and shore plover, all of us enjoying some unexpected late autumn warmth. Chatham Island warblers pick insects from the lichen and bull kelp thrown high on the coast during the recent storms. A Chatham Island fantail displays in the fringing Olearia trees and a pair of Chatham Island oystercatchers stand proud in the spray zone separated from the frolicking fur seals by a rolling ocean of breaking blue.

For us in the Chatham Islands, every day is an ‘Island Biodiversity Day’.