Don Merton’s legacy

Old Blue, from whom all other black robins are descended

Old Blue, from whom all other black robins are descended

Ornithologist Don Merton died on Sunday 10 April 2011, some 27 years after the black robin dubbed ‘Old Blue‘. Don pioneered conservation techniques of intensively managing the last remaining individuals of a species to recover the population and also of transferring species from one island to another, where habitats were more favourable and predators absent.

In the 1960s active management of predators and manipulating breeding at an individual level was not the done thing. Managing threatened species was pretty much a case of preserving habitat and then leaving them alone. An experience on Big South Cape Island in 1964 changed that. Rats got onto the island and Don and his colleagues transferred the only known South Island saddlebacks and the tiny Stead’s bush wren to nearby rat-free islands. The Stewart Island snipe and the greater short-tailed bat were not transferred and they soon became extinct. While the wren was transferred, it did not breed on its new home and it too ceased to exist.

Don later recalled: ‘The tragedy of Big South Cape was a timely and valuable lesson for us. It convinced even the most sceptical that predators could induce ecological collapse and extinctions. But it also has a massive, enduring impact because it shaped the way we developed policies about conservation and put them into practice.’

His most startling achievement occurred in 1976, when the remaining seven black robins on Little Māngere Island, one of the Chatham Islands, were transferred to nearby Māngere Island, which had better forest. As a young boy Don had successfully placed goldfinch chicks in his grandmother’s canary’s nest, which the bird then raised as her own. Using this age-old cuckoo’s trick as a cue, he gave the eggs of the last surviving female, named old Old Blue, to tomtits, which they successfully incubated. Old Blue would then lay another clutch. Slowly the population grew and so the species was saved – from just five individuals and one breeding pair. When Old Blue died at age 13 her passing was announced in Parliament. All of the 250 or so surviving black robins are descended from her and her breeding partner Old Yellow.

Few people could lay claim to saving a species, yet Don, as well as having a major hand in saving multiple bird species, also developed approaches that could be adapted for other threatened species. The Department of Conservation’s current recovery plans for threatened species build upon the work of Don and other conservationists of the late 1970s. The continued existence of the kākāpō and black robin are his most visible legacy, yet the hands-on approaches he and his colleagues developed, and that many others have since built upon, continue to offer hope for retaining biodiversity both in New Zealand and overseas.

In conservation circles Don Merton was not only world famous in New Zealand, he was world famous worldwide. And rightly so.

4 comments have been added so far

  1. Comment made by Megan || April 12th, 2011

    What were the genetic effects of starting with one breeding pair? Has such a restricted gene pool created problems? Did any of the other surviving Black Robins mate with the off-spring of Old Blue/Old Yellow? (I suppose the other survivors could have been related to Old Blue/Old Yellow anyway.)

  2. Comment made by Megan Huddleston || April 12th, 2011

    I came across Don’s story in one of the videos at the Zealandia exhibition. It is truly an amazing story and he leaves a tremendous legacy.

  3. Comment made by Carl Walrond || April 12th, 2011

    Megan – I’m not sure on the second question but on the first Don wrote in 1992 ‘genetic problems associated with prolonged,close inbreeding did not arise. (The species had presumably already survived an intense bottle-neck during its 90 year ordeal at perilously low numbers on Little Mangere.’

  4. Comment made by Trevor H Worthy || May 10th, 2011

    On the issue of genetic effects of a small foundling population – FAR too much empasis has been placed on the theoretical detrimental effects on individuals of a population derived from a small/tiny founding population. Most bird species that have derived from dispersal have derived from small nos of individuals and clearly in most this is not an issue. If Campbell & Trewick et al are correct in having most taxa in NZ derived from dispersed individuals setting up populations in NZ (and I am sure they are)then the majority of taxa in NZ derive from founding populations less than 10 or 20 individuals. Thus history suggests the theoretical issue is not so bad as it appears. The Black robin will be fine, as will takahe, saddleback, and numerous other birds whose populations have had severe bottlenecks caused by us meddling humans and their commensal rats etc.

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