by Emma Waterhouse
Coppermine Bay in the north of Te Paparahi,
looking towards Hauturu, Little Barrier Island. Source: K
This issue of
Environment News is late. While I could blame winter, lifeís usual
craziness, work and a myriad of other things, the truth is that I have
procrastinated on writing this editorial. And the reason is Rakitu.
case youíve missed it, the Department of Conservation (as this issue
goes to print) is about to drop brodifacoum-laced baits on Rakitu Arid
Island off Aoteaís north eastern coast. And many people are unhappy
about it. Many people also support it. The aim is to eradicate rats and
in doing so provide further predator free habitat for our indigenous
fauna and flora, including lots of birds. This approach works - on
Burgess Island in the Mokahinau Islands just north of Aotea seven
species of burrowing seabirds rapidly re-colonised the island following
pest eradication, and with little active management.
debate about Ďthe dropí appears to be becoming more acrimonious by the
day. Are personal attacks really what this is about? Apparently in this
debate you are a Ďproí or Ďantií poisoner. To cast this situation in
such a black and white manner suits many. But like most things, itís not
that straightforward. Nor are the very real trade-offs that are made if
we flat out reject poison as a means of predator eradication. We donít,
for example, have an alternative - yet - that will work at scale and at
a cost New Zealand can afford, and on the kind of terrain found on
Rakituís coasts. So the question really is, if we donít use poison in
some very limited instances, can our birds and other biodiversity wait?
Great Barrier isnít the first island or community to grapple with these
issues. The local board on Lord Howe Island looked thoroughly at all
methods available for their island, with a permanent population of about
400 people. The outcome - bait stations and hand broadcasting of bait in
as many areas as they could (including in and around settlements ) and
aerial poison on coastal and inaccessible, cliff areas. An independent
human health risk assessment was undertaken along with similar studies
on non-target species, the marine environment and tourism, and they
worked through community concerns.
eradication is now scheduled for next winter and would be the biggest
ever attempted on an inhabited island. If you are interested in some
very good information on the Lord Howe Island project, the research and
reports (including the history and approach to community involvement in
the decision making and a very interesting study on what fish do when
they encounter the baits) then head to the project website. Itís both
balanced and informative (lhirodenteradicationproject.org).
Overall, their studies conclude that there is a very low risk to human
health and the environment given the relatively small quantity of poison
to be used, in a Ďone-offí eradication.
Lord Howe work and other researchers note that, Ďone-offí use of
brodifacoum in an eradication program is very different in terms of
potential environmental effects when compared to ongoing sustained use.
the information I could find, it appears about 4-6 kg of pure
brodifacoum active ingredient are contained within all of the
brodifacoum products sold in New Zealand each year. Of the brodifacoum
sold, about 50% is used by private contractors. Other users are regional
councils (30%), the Department of Conservation (15%) and private
landowners (5%). Private contractors use brodifacoum as one of a variety
of tools, mostly in bovine tuberculosis (Tb) vector (possum and ferret)
control, regional councils at key biodiversity sites and the Department
of Conservation now only use brodificaum on offshore islands, mostly in
one-off rodent eradications.
So great is the loss of biodiversity in New Zealand that, when you get a
glimpse of its true richness, it takes you a while to recognise it.
Researchers also say that the risk of secondary exposure to native
non-target species is likely to be greater when brodifacoum is applied
to the environment in a sustained manner. I am much more concerned about
sustained ongoing use of brodifacoum in New Zealand than I am about
one-off rodent eradications, such as that planned for Rakitu (that will
deliver far more ecological benefit than cost) and those that have
already successfully rid large offshore islands of rodentsóand where no
poisons are now needed.
Ďantií poisoners seldom talk about the trade-offs of not using poison in
such situations. If the early conservationists (visionaries) in New
Zealand, and those that followed, had waited and not used poisons to rid
offshore islands of rats and stoats, then there is no doubt that many of
our iconic species would now be consigned to the museum. Thatís the very
the record, I donít like poison. But Iím also a scientist and in some
situations, I can accept a very low level of human and ecological risk,
based on the evidence to hand. And full consideration of alternatives
and consultation with affected communities. I also understand that no
level of risk, however low, is acceptable to some people. We also all
have a right, in this country, to express our opinions without fear.
Community members attend a bird monitoring workshop in Okiwi where the
for undertaking bird counts as well as the practicalities of counts were
presented and discussed.
leave you with an extract from an article by Dave Hansford on predator
free Fiordland in the New Zealand Geographic's latest issue that summed
up for me, why we do what we do:
great is the loss of biodiversity in New Zealand that, when you get a
glimpse of its true richness, it takes you a while to recognise it. As
we step ashore onto Chalky Island, we hear bird calls coming from the
riotous rātā forest above that I canít immediately identify - tīeke,
mohua, kākāriki. A falcon scuds overhead. And kererū; big flocks of
them. Wilson and I start to wend our way -carefully, because there are
seabird burrows everywhere - up through coastal scrub and into a bushy
myriad: rimu, matai, rātā, kāmahi, hutu. The sun spangles in the