South Pacific - Episode 02: Castaways

Description

The second instalment looks at how plants, animals and humans colonised even the most remote islands. Most pioneers came from the west, with New Guinea acting as the launch pad. The saltwater crocodile is one species which managed to swim the 60-mile crossing to the next island group, the Solomons. The mass spawning of groupers on a Solomon Island reef releases millions of eggs, which drift on ocean currents to establish new populations. The activity allows grey reef sharks to snatch a few distracted groupers. Few animals made it to Fiji, Tonga and Samoa, 1000 miles further east. Fruit bats were the only mammals to cross the ocean divide, but smaller animals were carried here by cyclones and jet stream winds. In the absence of ground predators, invertebrates have reached monstrous proportions. Fijian crested iguanas are thought to have floated here on rafts of vegetation. Seabirds have made the crossing to French Polynesia, where their rich guano helped fertilise barbed seeds stuck to their feathers and turn barren coral atolls into fertile groves. One plant needs no such help. Coconuts can survive drifting for two months at sea and lay roots into bare sand. Before the arrival of humans, fewer than 500 species colonised Hawaii in 30 million years. Once established, they evolved into countless new varieties. The story of human colonisation is no less remarkable. The ancestors of modern Polynesians, most probably Lapitas of Southeast Asia, arrived in Fiji 3,500 years ago and Hawaii 2,000 years ago.

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