Len Gillman: Sustainable harvest solution to kereru conflict

The kereru is a native New Zealand species protected under legislation. Photo / Supplied

Opinion

• Len Gillman is a professor of biogeography and head of science at Auckland University of Technology

We have a seemingly intractable conflict of ideas on our hands when it comes to the native wood pigeon or kereru. But are New Zealand's opposing attitudes to kereru really so irreconcilable? Sustainable harvesting could satisfy everyone's needs - a stance that many might consider surprising, coming from an avid conservationist.

The kereru is a native New Zealand species protected under legislation, but despite this protection it has continued to decline in abundance since European colonisation. As an iconic native species, it is treasured by many Maori and Pakeha as something that must be preserved at all costs.

However as a taonga (cultural treasure), tangata whenua are guaranteed full possession of kereru under the Treaty of Waitangi. Full possession implies ongoing rights of harvest, and so many assert that the Treaty imparts a right to harvest the bird in spite of legislation to the contrary.

Sustainable harvesting could provide the solution to the conflict that we have recently seen highlighted by the prosecution of Ngapuhi leader Sonny Tau for killing five birds and by last year's revelation that kereru had been served to three ministers of the Crown and 40 iwi leaders at a marae in 2013.

The main cause of kereru decline is predation and competition from mammalian pests, not hunting, and controlling these pests with natural poisons such as 1080 has been shown to promote their recovery. With ongoing predator control, populations increase until they reach a point where, limited by resources, surviving fledglings entering the local population roughly equal those leaving the population due to emigration and mortality.

When a population reaches stability, small harvests can be made without affecting the total number of birds, because those removed by harvest allow more fledglings to survive. This concept is known as a sustainable harvest - it allows a small ongoing harvest without affecting the size of the population. Harvesting quotas would need to be based on kereru numbers and age distributions, considering young birds learn survival skills from older birds, but sustainable harvesting holds great promise.

Harvesting quotas would need to be based on kereru numbers and age distributions.

Associated legislation and scientific monitoring could empower iwi to sustainably harvest kereru, by managing areas for pests and demonstrating that bird populations are healthy. In such areas, kereru could be maintained with substantially greater numbers than occur now. There would be more kereru, satisfying conservation objectives. Meanwhile tangata whenua would have an important cultural activity returned to them - allowing for the continuation of their matauranga Maori, via interaction with this taonga species, as guaranteed under the Treaty of Waitangi.

Combining scientific techniques such as population viability analysis with Maori ways of doing (tikanga) provides opportunities to not only manage taonga species into the future but also to develop co-management strategies that engage Maori in science and scientists in matauranga Maori.

The increasing number of young Maori studying conservation and ecology at universities is providing the necessary skill base for such an initiative. With iwi and scientists in control and co-managing this activity, I believe there would be little tolerance or appetite for illegal poaching of birds.