Abstract
T he Kaka Nestor meridionalis is a forest-dwelling parrot endemic to New Zealand. There are North Island and South Island Kaka sub-species. The North Island Kaka was once widespread throughout the North Island and outlying islands, but numbers have dwindled on the mainland to the extent that the only secure populations are on offshore islands.
The main reasons for the decline of Kaka on the mainland are habitat loss through deforestation, and introduced predators such as mustelids and opossums. Kaka were locally extinct from Mount Bruce reserve for nearly 50 years, until a bold new initiative to return them to the area. The reserve surrounds the Mount Bruce National Wildlife Centre, which is dedicat-
ed to the captive
breeding of New
Zealand's rare
and endangered
species for
release into the
wild. The initial
goal of the proj-
ect was "To
determine
whether or not
the release of
juvenile Kaka is
an effective tool
in the restoration
of Kaka to main-
land ecosys-
tems." Three
groups of juveniles from different origins were released in 1996 and 1997, and following the
success of these another release was undertaken in 1999, comprising adult males.
The first release group consisted of five wild-origin (Kapiti Island, Wellington) and four hand-reared juvenile Kaka. The Kapiti Island birds were captured and transferred to Mount Bruce in May 1996, and put into two aviaries with the handreared juveniles. Five were held in a large aviary with two captive adult Kaka, and four were held in a small temporary aviary at the release site.
During a one-month quarantine period, cloaca! swabs and fecal samples were collected from all nine Kaka, to screen for salmonella, yersinia, chlamydia and internal parasites including coccidia. All tests returned clear results. The birds were
fitted with transmitters (weighing 6% of the bird's body weight and with a 27-month life span) and individual colour leg band combinations.
In order to encourage the birds natural feeding behavior, the aviaries were supplied with fresh natural forage including berries and rotting logs which contained invertebrates. An aluminum feedstation identical to three feedstations which were to be set up at the release site, designed for ease of cleaning, was set up in each aviary so that the Kaka would become familiar with feeding from them. A diet of nectar, fruit, vegetables, seeds and nuts was supplied at the feedstations daily. The feedstations each consisted of a circular body divided into four feeding compartments, surrounded by pipe for the birds to perch on. Each feed station at the release site was secured 2 meters off the ground at the top of a metal pole, and could be easily lowered for cleaning. Food was supplied daily at 3:00 P.M. to the wild birds from the release date onwards.
The first release of nine birds occurred in June 1996. The juveniles spent the night before release all together in the temporary aviary at
the release site. The following morning the front mesh wall of the aviary was removed, freeing the birds. A morning release gave the birds time to investigate their surroundings before nightfall. Once the birds became accustomed to the daily 3:00 P.M. restocking of the feedstations, all but two wild-origin birds became regular feeders. Of the wild origin birds one was recaptured at the point of origin and a
second disappeared. A second release group, of five parent-reared captive-bred juveniles, was assembled and held at Mount Bruce in May 1997. These birds were prepared for release under the same protocols as the previous groups, with a quarantine, transmitter, band fitting, and feedstation set-up. They were held in the temporary aviary at the release/feedstation area for the three days prior to release, then released in June 1997 at the afternoon feed time. This meant that the 1997 release juveniles would see the resident wild birds using the feedstations. There was no difference in survival between the birds released in the morning and those released at the afternoon feed time.
All release groups were monitored using telemetry equipment during the six-month periods following release. Researcher Raelene Berry wrote her Masters thesis on the bird's behavior and survival, and found very little difference between the three release groups. All survived the sixmonth post-release monitoring period, and all remained within the Mount Bruce reserve, within approximately lkm of the release site. Two of the three sample groups had the benefit of parent rearing to learn their natural foraging techniques, however the hand-reared juveniles showed equal natural foraging abilities. All birds spent most of their feeding time chewing into wood for invertebrates, and were observed feeding on sap, fruits and nectar. The survival and site fidelity result showed there was little difference between the captive-bred and wild-origin juveniles, apart from less inclination from the wild-origin birds to use the artificial feedstations.