Some of the points made this article we first published in our
second edition of this magazine. Since that time (January 2005) the
plight of kiwi in NZ has steadily worsened. Now, more than ever, the
possibility of GBI as a kiwi sanctuary needs to be explored as a major
area of survival for this, our most iconic species.
Several species of kiwi evolved in the mammal-free Aotearoa of
pre-colonisation into the most mammal-like bird on the planet:
flightless and nocturnal, with external nostrils at the end of a long
bill and an exceptional sense of smell. Kiwi also have mammal-like bone
marrow, large ear openings
and loose hair-like feathers. The female lays proportionately one of the
largest eggs of any bird, which the male then incubates for 70-85 days.
This reversal of roles is associated with monogamy, a combination which
is extremely rare among birds.
The arrival of man brought introduced mammalian predators which have
decimated the kiwi’s breeding success and continue to dramatically erode
the adult populations. It is estimated that today’s total population
represents some 0.05% of the population before the arrival of humans
(and rats). Now every species is classified (by the Dept. of
Conservation) as “threatened”—some more, some less, e.g. the North Island
brown kiwi (although seemingly numerous at 20,000 (est.) individuals) is
in Category 4—Serious Decline.
Research has shown that the brown kiwi’s average life expectancy in
Northland is 13 years, whereas in other parts of NZ kiwi have been
calculated to live for 50 years. The impact of straying dogs is halving
their adult population every 10 years and decimating recruitment of
juveniles. Stoats are preying on the diminishing number of chicks with
The Whangarei Kiwi Sanctuary (WKS) has released some tragic statistics
from monitored populations in their sanctuary. The data indicates a
worsening trend for kiwi populations near human settlement.
• Kiwi deaths in the WKS have increased by 23% from the 2005 to 2006.
• 75% of adult kiwi that died in the WKS during the 2005/06 breeding
season were killed by dogs, up from 50% during the previous season.
(These statistics are based on fairly small numbers, but indicate a
Forest and Bird Organisation2 in their website piece “Kiwis facing
Extinction” put it bluntly:
“The situation is urgent. All mainland species of kiwi are threatened
with extinction unless the causes of the decline are addressed. Based on
present trends, kiwi could be extinct on the mainland in about fifteen
years —with the exception of five D.o.C kiwi sanctuaries and community
‘kiwi care’ efforts. Kiwi are already extinct in many areas, such as the
Manawatu, Wairarapa, Horowhenua, Marlborough and most of Canterbury and
Otago. There is a 3-6 year window to choose which remaining kiwi
populations we save and which we allow to become extinct. Unless the
survival rate improves, the kiwi’s decline will accelerate as existing
adult kiwi age and die. Populations without extensive predator control
do not produce enough chicks to replace the old kiwis as they die of old
Forest and Bird have identified “a shortage of money” as the single most
important barrier to kiwi conservation. These high costs include:
• The cost of establishing and operating sanctuaries
• Research on effective control of ferrets, stoats and cats
The issue of saving kiwi seems largely a political matter, although it
must be pointed out that there is no “magic bullet” on the horizon for
the control of ferrets, stoats and opossums.
Enter GBI—for the reasons outlined by John Ogden’s in the following
submission—the island of Great Barrier already has huge advantages as a
sanctuary: no mustelids or possums, suitable habitat, and the potential
for effective dog control. The huge costs of creating and maintaining
“mainland island” type of sanctuaries do not apply here—we have a moat
around us. A kiwi sanctuary on GBI is an economically achievable
Straying and wild dogs have been identified as the biggest single
predator of kiwi. Taborski3 an Austrian scientist, documented an episode
in Waitangi Forest (1988) where a single dog killed about 500 kiwi in a
few months. This is not an isolated incident. Of a reported 194 kiwi
deaths in Northland, there is documented evidence of 130 cases of dogs
killing kiwi—feral dogs, wandering pets, farm dogs and hunting dogs.
When questioned on the topic, Great Barrier Island dog owners invariably
reply that their dogs do not roam, are kept in at night, and are “not
even interested in birds” as many have done the bird aversion training.
Well and good, so we will point the finger at visitors’ dogs who might
take responsibility for the reported deaths this summer of little blue
penguins (Tryphena), oystercatcher adults and chicks (Medlands), and
possibly cooks petrels (Tryphena). These visiting animals could be
banned overnight if the political will existed. The control and
management of local dogs could be improved at the same time to contain
any ‘ferals’ without undue impact on the lives of responsible dog
Apart from the issue of dogs, the absence of mustelids (stoats, ferrets)
on GBI is a huge plus for kiwi breeding outcomes: research identifies a
kiwi’s first year as the most vulnerable period, when stoats and cats
kill about 95% of juveniles. Population decline would cease if about
twenty per cent of young kiwi survived to adulthood. Kiwi can bounce
back from this base as they live for about thirty years and can lay up
to 100 eggs in a lifetime.
The creation of a Kiwi sanctuary on GBI will not require any mass toxin
drop, will not require invasive quarantine measures and will not
inconvenience a single responsible dog owner. It could however ensure
the preservation of threatened kiwi species, ensuring our national bird
and symbol survives the invasion of humankind and our animal followers.
It is time to take action on this — the advantages of GBI as a kiwi
refuge far outweigh any possible disadvantages. The benefit to
conservation, and to the local economy through eco-tourism should ensure
strong community support.
1. Northland Kiwi Newsletter, Feb 2007, NZ Landcare Trust
2. Royal Forest and Bird Protection Society, Kiwis facing Extinction
website pp www.forestandbird.org.nz
3. Robertson, H.A. 2003: Kiwi (apteryx spp.) Recovery Plan 1996–2006,
Department of Conservation, Wellington.
4. Miller P.J. and Pierce R.J. Distribution and decline of the North
Island brown kiwi (Apteryx australis mantelli) in Northland, Notornis
42, 203-211 (1995)