Scientists Solve A Shag-adelic Bird Mystery

New Zealanders now get two endangered shags for the price of one.

    

By John R. Platt

March 25, 2016

New Zealanders have never been particularly enamored with their native shags. Anglers blamed the cormorants for stealing trout—an introduced species—and many colonies were destroyed to protect sports fisheries. One 1945 treatise, “The Shag Menace,” called for wholesale slaughter of the birds, with focused efforts during nesting and breeding seasons.Perhaps that’s why, compared with kiwis and other island birds, New Zealand’s dozen or so shag species have not been well studied. For many years, scientists couldn’t even decide how many shag species lived in New Zealand. One species, the Stewart Island Shag, exemplifies the confusion. First described in 1845, by British zoologist George Robert Gray, the Stewart Island Shag was listed as having two distinct populations, as well as bronze and pied morphs. While some ornithologists considered these one species, others dubbed them separate species or subspecies.

Recent research finally resolved the century-old debate. Scientists analyzed the birds’ genes and concluded that the Stewart Island Shag is actually two separate species: the Foveaux Shag (Leucocarbo stewarti), which lives on both sides of the Foveaux Strait between Stewart Island and South Island, and the Otago Shag (Leucocarbo chalconotus), which lives further to the east on South Island.

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