Stacey Balich

The tīeke breeding season started with a translocation of four eggs from nest boxes to Auckland Zoo. The zoo has a permit to take a small number of tīeke from the Island to supplement the captive population.

Taking eggs and raising chicks in captivity has several advantages over moving adult birds, not least the lack of stress to the birds.

The curator of birds at the zoo, Juan Cornejo, visited the Island in October and collected fertile eggs from three boxes. At least one fertile egg was left in each so the parent birds still had the opportunity to raise a chick.

At the zoo, one of the chicks had difficulty hatching and died shortly afterwards, but the other three, a female and two males, thrived under the care of zoo staff – 18 feeds per day at first! They are now healthy juveniles and will eventually be on display in the forest aviary.

On the Island, monitoring was disrupted by wild weather and consequent ferry cancellations, but it was clear that nest box use and rates of success and failure followed the pattern of the last few years.

Nesting attempts were made in 22 of the 151 boxes, and 10 of these failed at egg stage (the eggs failed to hatch or were broken). As far as we can tell, none failed at chick stage and at least one chick fledged from each of the remaining 12 boxes, including two of those from which eggs had been translocated in October.

My first venture down the slope behind the Fog Horn shed brought me to a little grassy patch where my tripod could stand. Peering through the telescope it was not clear whether all the squatting red-billed gulls were on nests, but this twin-peaked rock, just south of the bay, was obviously a favoured breeding site. Weaving a heavy tripod through a tangle of flax and cabbage trees was a bit cumbersome but, on reaching the northern side of this little promontory, a large curl-shaped rock came into view with a colony of gulls dotted along its ridge line and, below me, binoculars revealed a small rocky platform crowded with busy occupants and obvious nests.

I’d been invited to assess the breeding numbers of common inshore seabirds around the coastal fringe of the island. How do you view our coast from the land? So many steep bush-clad slopes and hidden gullies! Old hands will have known much of the territory but for me, it was an exciting new exploration. In that first year, I located a small colony of black-backed gulls on a handful of rocky islets just off the North-east Bay track. As I ate lunch, after counting those gulls a reef heron carrying fish flew into the bay. On landing, two juveniles came scrabbling out of the bushes to meet the parent – the only proof of its breeding in the ten years this survey has now run.

Carne Blandy, Oscar Thomas and Rachel Taylor each helped for a season in different years but for the last 5 years Roy Gosney and I shared this work together; making about 8 visits each season to gauge the build-up and peak of breeding numbers. Access to the two black-backed gull colonies, long established on the west coast, can be fun. Coprosma completely hides the access to the one below the Papakura Pa site, so I dread to think what visitors thought if they caught sight of two old buffers emerging from a dense thicket! And getting to the rocky outcrop at North-west Point has also become an adventure as the track dwindles and we two disappear into the ever-burgeoning flax and twiggery; but it’s well worth the scramble, to arrive in the quiet atmosphere of the little grassy plateau overlooking the breeding site and up the Tiritiri Matangi coastline northwards.

Whilst the two gull species are always present, their breeding numbers vary, red-bills between 100 and 350 pairs, black-backs between 30 and 45. The Pied-shag colony remains fairly static with 6-8 nests, but tern numbers are the least predictable with a single paid of Caspians in just 2 or 3 survey years and white-fronted tern ranging from none years to 120 pairs at best. Our Biodiversity Team wants to monitor these common birds as well as the rarer species our island hosts.

In July I move to Cambridge and have to leave Roy to do next seasons counting. I’m sure he would welcome a new survey partner. It’s been a joy and privilege to explore some of the hidden parts of Tiritiri Matangi and share that experience with others. For this wonderful place and the lovely people I’ve met here, I give thanks!

Kiwi pukupuku/ little spotted kiwi were first introduced to Tiritiri Matangi in 1993 (10 birds) with a further 6 released in 1995. Two birds were lost early on but 14 went on to contribute to the genetic pool.

As part of the population monitoring of this translocated species, Supporters of Tiritiri Matangi first conducted a kiwi call survey in 2009 and have subsequently done so in March of every year, apart from 2012, 2015 & 2020.

During the survey, Supporters of Tiritiri Matangi volunteers are stationed at ten listening spots around the island. The survey starts twenty minutes after sunset and lasts for two hours. Listeners record the time a call is heard, the sex of the bird calling and the compass bearing and approximately distance of the call, from the listening site. The listening sites are the same from year to year and the survey takes place when there is no moon during the survey hours.

The survey is conducted to collect trend data on approximate kiwi numbers and by surveying every year, we can pick up short-term variations. There is also value in the survey enabling Supporters of Tiritiri Matangi volunteer participation.

Listeners also record ruru/ morepork call during the survey. John Stewart surveys ruru numbers during their breeding season and recording call locations during the kiwi call survey helps him identify areas of bush where ruru are holding territory.

There are some challenges for the survey volunteers. Fearing the dark is an instinctual survival mechanism for humans, so standing alone, outside on the island at night can sometimes bring on a mild case of the heebie-jeebies. Some nights can be bitterly cold, especially if there is wind, and boredom can creep in if the listening site is less active for calls. Conversely, if the site is very active, it can be challenging to record calls coming in quick succession. Differentiating male & female calls can also be tricky when the wind is stronger or if the calls are heard a long distance away.

Offsetting the challenges, there are also some pleasures of being out at night on the survey. There is often quiet time to appreciate the night sky and the calls or sightings of other island nightlife such as insects, reptiles and sea birds. The occasional close encounter with kiwi is always a highlight.

In addition to the annual kiwi survey, a 5-yearly survey is conducted in conjunction with the Department of Conservation Dogs NZ. During this survey, kiwi are caught & banded. The 5-yearly survey gives a more accurate indication of numbers but is more expensive and logistically challenging to organise.

The last 5-yearly survey took place in 2022 and estimated the kiwi population on Tiritiri Matangi to be around 80 birds.

Kiwi pukupuku calls

Male & female kiwi calls are different. The male gives a high-pitched ascending whistle, whilst the female gives a slower and lower-pitched ascending trill. Both sexes repeat their calls up to 35 times per sequence.