The Black Robin Project - November 5th

Rangatira Island is a great place to research some of New Zealand’s native songbirds – black robins, Chatham Island warblers and Chatham Island tomtits. The black robins are the best studied of this group. Once upon a time they were the rarest birds in the world, with a small population restricted to Little Mangere Island, a tiny rock not far from here.

In the early eighties, just before the last of the forest died on Little Mangere, the last remaining robins were moved to Mangere Island and then to Rangatira where their breeding could be managed. At one stage there were only five birds alive, and only one female who produced fertile eggs. Conservation workers used tomtits and warblers as foster parents so that more black robin eggs could be incubated and hatched in one season. They managed to increase the number of robins into double figures. Now you can’t walk through the Rangatira bush without black robins following you from branch to branch.

The team here does not actively manage the breeding of the robins, but helps DOC to keep an eye on how the birds are doing. Most of the work involves following robins to find their nests, and checking them every few days for eggs and then chicks. We also search for Chatham Island warbler and tomtit nests.

Part of Melanie’s research looks at the effects of predators on the habits of songbirds. On mainland NZ, songbirds sit for much longer on the nest. Moving about and getting on and off the nest can attract the attention of cats, rats and stoats so the birds tend to stay pretty still, and when their chicks hatch they will only visit the nest to feed them three or four times an hour. Although it was farmed for many years, Rangatira Island has never had any introduced predators. The songbirds here move on and off the nest all day, and can feed their chicks up to twenty times an hour. To quantify this, nests are filmed for six hour periods at two stages during the breeding season: once nine days after the eggs are laid and again when the chicks are about 10 days old.

Learn more about Dr Melanie Massaro's research at the School of Biological Sciences at the University of Canterbury: http://www.biol.canterbury.ac.nz/people/massaro.shtml.