Penguin numbers tumbling

Forest and Bird, Issue 280, 1 May 1996, Page 4

Penguin numbers tumbling

Alan Tennyson

A SURVEY OF the remote Antipodes Islands in the New Zealand subantarctic last November indicates a catastrophic decline in the number of penguins over the past century. Two species of penguin nest at this island group — the erectcrested and the slightly smaller rockhopper. It seems that the populations of both species have declined but that rockhoppers have suffered the most. Preliminary calculations from last year’s counts came up with totals of 50,000 to 60,000 erectcrested and less than 4,000 rockhopper pairs. This is down from estimates published in 1990 of 115,000 erect-crested and 50,000 rockhopper pairs. Early photos going back to the 1920s show huge colonies of rockhoppers where now only a handful of birds remain. The decline in rockhopper numbers was not entirely unexpected. Surveys of New Zealand’s other rockhopper colonies on the Auckland and Campbell Island groups show similar declines. The best documented is that at Campbell where numbers have declined by 94 percent since the 1940s.

Researchers believe that sea temperature increases, | possibly as a result of the Greenhouse effect, have affected the bird’s food supply and led to the decline.

While the remaining colonies of penguins are still spectacular on places like the Antipodes, the outlook for these penguins in our region seems bleak. If the current rate of decline continues, rockhoppers will become extinct in the New Zealand subantarctic within a few decades. Hopefully the species itself is more secure as rockhoppers occur on several islands around the southern ocean and declines have not been detected outside the New Zealand region. Perhaps more of a worry is the erect-crested penguin which although apparently not declining as rapidly, is almost entirely confined to nesting on the Antipodes and nearby Bounty Islands. A survey of the Bounties is needed to determine the current status of the species there.