Geography of New Caledonia a refugium, in effect a biological "Noah's Ark", an island home to both unique living plants and animals and also to its own special fossil endowment. Birds such as the crested and almost flightless kagu (French, "cagou") "Rhynochetos jubatus", whose closest relative may be the distantly related sunbittern of South America, and plants such as "Amborella trichopoda", the only known member of the most basal living branch of flowering plants, make this island a treasure trove and a critical concern for biologists and conservationists. The island was home to horned fossil turtles ("Meiolania mackayi") and terrestrial fossil crocodiles ("Mekosuchus inexpectatus")
Kagu 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. 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