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Stitchbird / hihi (Notiomystis cincta)

Mohamed bin Zayed Species project number 11253113

Mohamed bin Zayed Species Conservation (Project No. 11253113) - Stitchbird / hihi - Awarded $10,000 on February 07, 2012

In March 2013, 23 male and 21 female hihi, Notiomystis cincta, were translocated to Bushy Park sanctuary, near Whanganui, New Zealand, from Tiritiri Matangi Island, near Auckland. The primary purpose of the translocation was to establish another viable population of hihi in its presumed former range on the New Zealand mainland. Once relatively common across the North Island of New Zealand, hihi were reduced by the mid-1880s to a single population, offshore on Te Hauturu o Toi/Little Barrier Island. Since 1980, the species has been translocated to a number of other sites in an effort to establish additional populations, but with varying success. At the start of the present project, hihi were present in the wild at just six sites, three islands (Hauturu, Tiritiri Matangi, Kapiti) and three mainland sanctuaries (Karori, Maungatautari and Ark-in-the-Park).

Bushy Park is a mainland sanctuary comprising 87 ha of near-pristine lowland temperate rainforest and 11 ha of rough pasture, formal gardens, and a historic homestead and adjacent buildings. Despite its small size, the sanctuary was considered to be an appropriate release site for various reasons: suitable forest habitat free from non-native predators other than mice; successful past reintroductions of North Island robin, Petroica longipes, and North Island saddleback, Philesturnus rufusater; well-maintained and secure infrastructure, including a predator-exclusion fence; and a community of volunteers willing and able to support the reintroduction by setting up and maintaining a network of feeding stations and nest boxes, as well as monitoring the birds.

Because Bushy Park is largely surrounded by open pasture, the release also provided the opportunity to address one of the uncertainties in the hihi recovery programme: whether the open ground around the forest would inhibit the dispersal of hihi from forest. Reintroductions elsewhere on the mainland have resulted in some individuals moving far beyond the release site, occasionally into neighbouring forested areas where predator control is less intensive and the birds can become isolated. If hihi will not cross open ground, then an optimal release site could be one where the birds' forest habitat is relatively isolated, all else being equal. Forty of the birds were radio-tagged and, following their release, were tracked for a month, the lifetime of the transmitters. Only one of these individuals left the park, and then only temporarily, visiting a small (4.3 ha) contiguous patch of forest on five occasions and venturing once down an avenue of trees along the entrance driveway. She returned to Bushy Park on each occasion. Later, one male was also seen along the driveway, but also returned to the main forest. Both individuals eventually settled inside the forest proper. There is no evidence that any hihi dispersed permanently from the sanctuary.

Over 2900 unique sightings of colour-banded hihi have been catalogued since the initial release, giving us detailed insight into the movements, survival and relationships of these birds.(A 'unique sighting' is a known individual seen a one location on one day; duplicate sightings at the same location on the same day are not counted.) These data have been used by an MSc student for her thesis. One paper has been submitted; another is being prepared. 

Based on these data, we know that only six females (29%) survived the first 6 months following release, in contrast to 17 males (74%). Of these females, 4-5 bred during the first breeding season (2013/14), 3-4 of them successfully (the uncertainty comes from birds apparently breeding in natural cavities, but whose nests were never found). A total of 15-18 chicks fledged successfully. The following breeding season (2014/15), at least 11, possibly 12, breeding attempts were made by eight females: two surviving females from the initial release; five first-year females from the 2013/14 breeding season (including one unbanded bird); and one, possibly two, females whose identities are not known for certain and whose nests were never found. At least 30, but possibly as many as 33 chicks fledged, 25 of which were banded. The variation again reflects uncertainty about just how many chicks fledged from undiscovered nests in natural cavities, based on subsequent sightings of unbanded birds. Midway through the third breeding season (2015/16), a further 28 chicks have fledged from 11 breeding attempts (including two outright failures); at least seven females are currently (January 2016) building second nests, incubating second clutches, or rearing their second broods. Forty-three boxes have been put up in the forest to ensure that nest-site availability is not a limiting factor, and to enable close monitoring of nesting success. Over 85% of all nesting attempts have been made in artificial nest boxes. Nests in natural cavities are extremely difficult to find.

Successful breeding and recruitment has been helped by supplementary feeding. Sugar water, equivalent to a 17% sucrose solution, near the median sugar concentrations of nectar of bird-pollinated flowers, is being provided at five feeding stations as a supplementary food source. This not only covers any periods of nectar shortage but also helps offset the birds' energetic costs of foraging for insects, allowing them to maximise the use of these foods for productive purposes. The sugar water is replenished every three days by teams of volunteers working to a three-week roster, and has ensured wider public engagement in the successful re-establishment of hihi in yet another part of its former range.

Despite the high breeding success achieved so far, there is concern about the narrow genetic base from which the current population stems, a consequence of the low survival of the translocated females. Plans had been made to have a follow-up translocation in early 2015 but this was suspended when an incursion of rats was detected in November 2014. An intensive programme to eradicate these rats was immediately implemented and was apparently successful, with the incidence of rats being reduced to much less than 1% by February 2015 (as determined by tracker-card monitoring). Five audits carried out since August 2015 at 4-7 week intervals have not detected the presence of any further rats. This heartening result suggests that we are on track to restoring the park's previous rat-free status. Nevertheless, the follow-up translocation is on hold until biosecurity measures have been assuredly strengthened and can be sustained.

Overall, this project to re-establish another viable population of hihi in one more mainland sanctuary in New Zealand has been a qualified success, one that we hope will endure and allow Bushy Park in turn to become a source of birds for other sanctuaries. The success of this project would not have been possible without the generous financial and material support of numerous organisations and individuals, not least of which was that granted by the Mohamed bin Zayed Species Conservation Fund. Not only did this funding underwrite some of the substantial translocation and monitoring costs, it also helped leverage additional funds from other sources. The Bushy Park Trust and all those volunteers involved in this project express their gratitude to the Fund for its support.

Copies of project newsletters and reports are available at http://www.bushyparksanctuary.org.nz/news.

 

Project documents