Estuaries and tidal flats are populated with varieties of mangroves (39 of the 47 Northern Territory species of mangrove occur in Kakadu) that are important for stabilising the coastline. Mangroves serve as feeding and breeding grounds for many fish species including the barramundi. On the tidal flats behind the mangroves, hardy succulents (samphire), grasses and sedges grow. Isolated pockets of monsoon forest grow along the coast and river banks. These forests contain several impressive trees, among them the banyan fig, which can be recognised by its large, spreading aerial roots, and the kapok tree, which has a spiny trunk, large, waxy red flowers and pods full of cotton-like material. The diverse environments of Kakadu National Park supports a great array of animals, a number of which have adapted to particular habitats. Some animals in the park are rare, endangered, vulnerable or endemic. Responding to the extreme weather conditions experienced in the park, many animals are active only at particular times of the day or night or at particular times of the year. About 74 mammal species—marsupials and placental mammals—have been recorded in the park. Most of them inhabit the open forest and woodlands and are nocturnal, making it difficult to see them. Others, such as wallabies and kangaroos (macropods, 8 species), are active in the cooler parts of the day and are easier to see. Among the larger more common species are dingoes, antilopine kangaroos, black wallaroos, agile wallabys, and short-eared rock wallabys. Smaller common mammals are northern quolls, brush-tailed phascogales, brown bandicoots, black-footed tree-rats, and black flying foxes. Dugongs are found in the coastal waters. However, recent surveys have revealed a disturbing decline of nearly all mammal species throughout Kakadu, including once common and widespread species such as northern tart bats. Kakadu's many habitats support more than 280 species of birds, or about one-third of Australia's bird species. Some birds range over a number of habitats, but many are found in only one environment. Some 11,246 km2 of Kakadu's savanna habitats has been identified by BirdLife International as an Important Bird Area (IBA) because it supports populations of the endangered Gouldian finch, the vulnerable red goshawk, the near threatened partridge pigeon and chestnut-backed button-quail, and the restricted-range hooded parrot and rainbow pitta.