Kagu

Kagu are territorial, maintaining year-round territories of around 10–28 hectares (22–62 acres). Within the territory the pairs are solitary during the non-breeding season, and may have separate but overlapping foraging areas. Kagus make a range of different sounds, most commonly while duetting in the morning, each duet lasting about 15 minutes. The kagu's crest and wings are used in territorial displays towards other kagu, slightly different displays are used towards potential predators. Territorial disputes may be resolved by fighting using wings and bills, in the wild this seldom results in serious injuries.

The kagu is endemic to the forests and shrubland of New Caledonia. Within that island group it is restricted to the main island of Grande Terre. There is no evidence that it occurred on the Loyalty Islands, although fossil remains of the extinct lowland form R. orarius have been found on the Ile des Pines. The kagu is a habitat generalist and able to exist in a range of different forest types if sufficient prey is present, from rain forest to drier lowland forest. They are also able to feed in some drier shrubland associated with the island's ultrabasic rocks, although not in the poorest, low-prey shrubland of this type. They are also absent from areas where extensive ground cover makes foraging difficult, such as grassland or areas with high fern cover, but may pass through such areas to reach other foraging areas. The species has undergone some range contraction due to hunting and predation by introduced species. Its original, pre-human distribution, and the extent to which it and its sister species R. orarius coexisted in lowland areas of New Caledonia, is still not fully understood and awaits further research into the subfossil record.

The kagu's initial decline was caused by subsistence hunting. The bird was trapped extensively for the European pet trade and for museums and zoos until it was afforded protection. It is threatened by introduced cats, pigs and dogs. New Caledonia lacked mammals (except for bats) before the arrival of humans, and many of its native species have been negatively affected by introduced mammals. Rats have a big impact on nestlings, accounting for 55% of nestling losses. Kagus also suffer from habitat loss caused by mining and forestry. Concern was first raised about the future of the kagu in 1904. A visiting American scientist noted in 1948 that the extinction of the species was probable, and identified the many threats the species faced. The first concrete evidence of the impact of dogs came when a New Zealand researcher's study population was quickly exterminated by dogs in the 1990s, although suspicions about the importance of dogs and other predators had been voiced before this and dog control measures had been enacted in some areas in the 1980s. The kagu is listed as endangered (CITES I) and enjoys full protection in New Caledonia. It has been the subject of dedicated conservation efforts and is receptive to ex-situ conservation, breeding well in Nouméa Zoo. It is also prospering in Rivière Bleue Territorial Park, which has a pest-management programme and has been the site of releases into the wild of captive-bred birds. Recent research has shown that naturally occurring heavy metals in the soil may affect Kagu through their food supply. Kagu in areas where soil levels of heavy metals were low laid more eggs and had higher numbers of fledglings, as well as having smaller home-ranges and higher body mass, than Kagu in areas where the soil was heavy-metal rich. It has therefore been suggested that Kagu conservation is likely to be more effective in areas where heavy-metal levels in the soil are low.