by Emma Waterhouse
Seabirds off the west coast
of Aotea/Great Barrier. The island sits on the ‘Seabird Super
Highway’— a chain of islands, mostly predator-free, that
stretches along the North Island’s east coast from the Three
Kings Islands to the Bay of Plenty.
Photo: Karen Baird.
just returned from the Glenfern Walk in Port FitzRoy and was lucky
enough to spy a black petrel chick in its burrow under an old gnarled
puriri tree. What a treat, although I suspect the chick did not share my
enthusiasm! Glenfern Sanctuary is now an Auckland Council regional
park, under the management of a newly formed trust, charged with
developing and enhancing the sanctuary for conservation, education and
It’s great to see Glenfern ‘open for
business’ once again. The low predator numbers in the Glenfern Sanctuary
(and wider Kotuku Peninsula Sanctuary) are a major reason black petrel
(and Cook’s petrel) have bred there in recent years. Although these
seabirds may well have nests in other isolated parts of the island,
Hirakimata/Mt Hobson remains as the main breeding population for black
petrel, New Zealand’s most ’at risk’ seabird.
A real and relatively immediate
possibility exists for a second viable population on Aotea/Great Barrier
to become established—this time on Rakitu off the island’s east coast.
For over a decade there has been talk of eradicating rats and other
predators off Rakitu (see timeline on page 20), yet action on the ground
continues to be sadly lacking.
The island sits at a mid point on the
North Island’s east coast ’seabird superhighway’ (see page 4), a chain
of predator-free islands that stretch from the Three Kings Islands to
the Bay of Plenty (see map at right). It’s no coincidence that these
islands host breeding colonies of over 25 species of seabird, a true
biodiversity hotspot, with more pest-controlled mainland areas such as
Bream Head, and recently pest-free islands like the Mercury group likely
candidates for colonies to become established in the future.
It’s not hard to see that Rakitu is
ideally placed on the seabird highway, and expert opinion suggests that
at least six species would become established there following the
removal of rats (and weka). Just look at the rapid colonisation of
Burgess Island in the Mokahinau group (see page 7), with seven species
of burrowing seabirds now present following pest eradication, and with
little, if any, active management. This model of ‘passive restoration’
could also work on Rakitu, but not if the current population of weka
remain. Alternatives exist to relocate these birds elsewhere (see page
9). The stock of islands that could host breeding populations of our
most vulnerable seabirds is, in contrast, severely limited.
While some progress is being made, the planned rat
eradication is likely to be delayed yet again, until 2018. And we
understand that the weka are to remain. Why? Weka equals no seabirds,
which, we assume, was one of the groups of species identified as a major
beneficiary of the eradication in the first place!
The cliffs and forests of Rakitu once rang out with
the calls of thousands of seabirds—and they can once again. But the
Department of Conservation needs to get the job done now, using the
Recent research for the Hauraki Gulf and elsewhere clearly demonstrates that support for pest eradication and
ongoing management is closely related to a community’s first hand
experience of such programs, and very importantly, the outcomes they
bring. So as the Rakitu story plays out, what we do know is that there
must be clear objectives for management of the island following the
eradication, including how iwi and the Aotea/Great Barrier and wider
community, are to be involved. These groups all have an interest and
stake in the future of Rakitu.
Meanwhile on the Aotea mainland, the Trust has been
active in managing a rat monitoring program on Hirakamata. Volunteer
support has been critical to this effort which has so far returned some
interesting results (see page 18). Rats are a serious threat to birdlife
and seem to have well and truly adapted to mountain life! Monitoring is
We hope you enjoy reading this newsletter
and gratefully acknowledge the support of the Great Barrier Local Board
with funding to produce our first full colour Environmental News.
Seabird colonies along the east coast of the northern North Island.
Most of these colonies occur on islands free of predators or in predator
controlled areas, like Glenfern Sanctuary on Aotea/Great Barrier. A
predator-free Rakitu would provide another (obvious) link in this island
chain, described by ornithologists as a ‘seabird super highway’.
Figure credit: H. Unkovich & E. Waterhouse
Cuvier Island (left)
and Mercury Islands (in the distance) from Kaitoke. Like Aotea/Great
Barrier, both sit squarely on the seabird super highway—but unlike
Aotea, are pest-free. Rakitu, off Aotea’s east coast, has been earmarked
for rat eradication for over a decade. With the removal of rats (and
weka), the island could provide another important link in the chain of
seabird islands along the North Island’s east coast. Photo: E.