Ganges Delta trees are found in these areas. The delta region has mangrove trees. It is estimated that 30,000 chital ("Axis axis") are in the Sundarbans part of the delta. Birds found in the delta include kingfishers, eagles, woodpeckers, the shalik ("Acridotheres tristis"), the swamp francolin ("Francolinus gularis"), and the doel ("Copsychus saularis"). Two species of dolphin can be found in the delta: the Irrawaddy dolphin ("Orcaella brevirostris") and the Ganges river dolphin ("Platanista gangetica gangetica"). The Irrawaddy dolphin is an oceanic dolphin which enters the delta from the Bay of Bengal. The Ganges river dolphin is a true river dolphin, but
Endangered species future. The introduction of non-indigenous species to an area can disrupt the ecosystem to such an extent that native species become endangered. Such introductions may be termed alien or invasive species. In some cases the invasive species compete with the native species for food or prey on the natives. In other cases a stable ecological balance may be upset by predation or other causes leading to unexpected species decline. New species may also carry diseases to which the native species have no resistance. Captive breeding is the process of breeding rare or endangered species in human controlled environments with restricted