Chatham Islands - Ecology

Ecology

The natural vegetation of the islands was a mixture of forest, scrubby heath and swamp, but today most of the land is fern or pasture covered, although there are some areas of dense forest and areas of peat bogs and other habitats. Of interest are the macrocarpa trees, with branches trailing almost horizontally in the lee of the wind. The ferns in the forest understory include Blechnum discolor.

The islands are home to a rich bio-diversity including about fifty endemic plants adapted to the cold and the wind, of which Chatham Islands forget-me-not (Myosotidium hortensia), Chatham Islands Sow-thistle (Embergeria grandifolia), rautini (Brachyglottis huntii), Chatham Islands kakaha (Astelia chathamica), soft speargrass (Aciphylla dieffenbachii) and Chatham Island akeake or Chatham Island tree daisy (Olearia traversiorum) are among the best-known.

The islands are a breeding ground for huge flocks of seabirds and are home to number of endemic birds, some of them seabirds and some of them living on the islands themselves. The best known species are the Magenta Petrel and the Black Robin, both of which came perilously close to extinction before being subjected to conservation efforts. Other endemic species are the Chatham Oystercatcher, the Chatham Gerygone, the Parea or Chatham Pigeon, Forbes' Parakeet, the Chatham Snipe and the Shore Plover. A number of species have also gone extinct since European settlement, including the three endemic species of rail, Chatham Raven and the Chatham Fernbird.

There are also a number of endemic insects while mammals found in the waters of the Chathams include New Zealand Sea Lion, Leopard Seal, and Southern Elephant Seal.

Much of the natural forest of these islands has been cleared for farming, but Mangere and Rangatira Islands are now preserved as nature reserves to conserve some of this unique flora and fauna. Another threat to wildlife here comes from introduced species which prey on the indigenous birds and reptiles, whereas on Mangere and Rangatira livestock has been removed and native wildlife is recovering.