Editorial: Browsing birds left mark on land

Moa garden in Christchurch.

Just the other evening on January 13, TV One announced that Canterbury Museum work using "state of art 3D modelling" has given greater insight into New Zealand's vegetation prior to humans migrating here and how the vegetation had evolved.

The museum's curator, Professor Paul Scofield, said the giant moa had a very strong bill (with) the ability to bite through thick twigs and sticks, but some small moas probably were grazing very much like sheep. The nine species of moa utilised the vegetation and had a considerable browsing impact. Moas became extinct 500 years ago due to hunting by Maori and fire destruction of their habitat by Maori and natural causes.

"They probably created much more open forest, eating under-storey, biting through thick sticks. We strongly suspect that what we called pristine forest is nothing like the pristine forest prior to human arrival," said Professor Scofield. "It has implications for conservation efforts going forward."

Until late last century, the view was pushed by government departments, mainly the Forest Service and its successor the Department of Conservation, that New Zealand's vegetation had "evolved in the absence of browsing animals". Whether animals or birds, matters little. Browsing was commonplace for millions of years.

World-eminent New Zealand ecologist the late Dr Graeme Caughley at a 1988 seminar spelt out that New Zealand's plant-herbivore systems underwent three ecological stages. He said "New Zealand has seen three browsing regimes over the last 1000 years: the period of moa browsing up to 1400, the interregnum 1400-1850 and the period of mammalian browsing (eg, deer) since 1850." Much of New Zealand's conservation efforts of the last 80 or so years have therefore been mistakenly directed at getting rid of "pests", a tag applied by departments and the vocal Forest and Bird Society, to mammals such as deer and possums. Late in the 1950s, Dr William Graf, a Californian Professor of Zoology, came to New Zealand to study the wild deer situation as Hawaii was considering introducing deer for sport. Conflicting information about New Zealand deer herds and their reputed problems prompted the Hawaiian Board of Agriculture to send the scientist to study the situation firsthand. In his report following the visit, Dr Graf wrote that there existed in New Zealand an "anti-exotic animal phobia, to an extent that much of the public as well as many government officials do not and cannot view the situation in an objective perspective". The bureaucracies were incensed.

What of the moa? The demise of the moa after it being a major browsing factor for many millions of years, resulted in New Zealand's vegetation entering an "unnatural" state. In short New Zealand's vegetation had developed over many, many centuries under intense browsing by herbivore birds including moas and others such as the native pigeon (kereru), takahe and others. Once deer - and other wild animals - were established, the vegetation and bush became more like its original state of the moa era, because browsing was restored into the ecosystem. Possums have been labelled as a "rapacious consumer of all things green" but in 1994, a senior Landcare Research scientist Graham Nugent told a DOC "Possum Pest" workshop that the department was wrong. He dismissed DOC's guess of a national possum population of 70 million as "a back of a cigarette packet calculation". Yet the misconception of wild animal pests has resulted in costly "conservation efforts" that have involved hired deer killers, uncontrolled helicopter-based commercial deer slaughter and the use of ecologically damaging poisons such as 1080. The findings and revelations of the Canterbury Museum work has indeed very big "implications for conservation efforts going forward", as Professor Scofield put it. New Zealand's vegetation by its evolution over countless millions of years from eras of herbivore dinosaurs to herbivore moas and now herbivore game animals needs browsing vital to the ecosystem's functioning. Hunters don't want large numbers of deer beyond the habitat's carrying capacity. They merely want common-sense management policies compatible with reality and the health of vegetation - and an end to damaging ecosystem poisons like 1080.

-Laurie Collins is spokesman for Sporting Hunters Outdoor Trust and is a West Coast based conservationist.

-Business and civic leaders, organisers, experts in their field and interest groups can contribute opinions.

The views expressed here are the writer's personal opinion and not the newspaper's. Email: editor@hbtoday.co.nz-A Talking Point by Hawke's Bay Regional councillor Tom Belford in yesterday's paper was significantly edited. For the full version go to hbtoday.co.nz.