Reintroducing hihi (Notiomystis cincta) to the New Zealand mainland : a thesis presented in partial fulfilment of the requirements for the degree of Masters of Science in Ecology at Massey University, Palmerston North, New Zealand
This thesis investigated the potential for establishing a self-sustaining population of an
endangered forest bird, the hihi (Notiomystis cincta) on the New Zealand mainland, and
the factors that may influence this. Previous reintroduction attempts, mostly to offshore
islands, have met with limited success, or been dependent on ongoing management.
However, future conservation measures for hihi aim to reintroduce populations to the
mature forest found on the mainland that hihi may be best adapted to. Such
reintroductions come with new challenges for hihi conservation.
The first reintroduction of hihi to this environment occurred with two releases of hihi
from Tiritiri Matangi Island to “Ark in the Park”, a predator-controlled site in Auckland’s
Waitakere Ranges, in February and June 2007. This study reports on the survival and
dispersal of hihi following these releases, using radio transmitters for post-release
monitoring, and also gives information on the vulnerability of hihi to predators, and
foraging behaviour at this site.
In terms of survivorship, birds released in February had higher apparent survival than
those released in June, but this may have been due to higher dispersal in June. Birds
released under a “delayed-release” strategy had lower long-term survival than those
released immediately. There was some evidence that transmitters may have had an impact
on dispersal and behaviour, but there was no evidence that transmitters reduced survival.
Individuals in better condition were more likely to disperse further in the first week postrelease,
but it was not possible to examine the relationship between condition and
survival. Clutch size and hatching date were the two most influential factors found to
affect individual condition in juvenile hihi from Tiritiri Matangi Island. It may be
possible to use this information when selecting individuals for future translocations, but
the impact on the source population should first be investigated, as well as the
relationship between condition and survival.
The failure of previous hihi reintroductions has in part been attributed to a lack of
diversity of natural food in regenerating forest, and all successfully reintroduced
populations to date rely on supplementary food. However, little is known about how the
diet of hihi changes at different life stages, between the sexes, by season and in different
habitats. In this study, such information was provided for the first time for hihi using
stable isotope analysis. I found evidence for dietary shifts across different life stages
(nestling, fledgling, juvenile and adult), between the sexes, and in different habitats
(regenerating forest vs mature forest), and I showed that diet may be one of the proximate
factors influencing individual condition.