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
Asystasia gangetica it has become naturalized. Both subspecies of this plant have been introduced to Australia where "A. g. micrantha" is on the National Environmental Alert List and must be reported when found. The original range of the subspecies is unclear, but it is likely that "A. g. gangetica" was limited to Asia, and "A. g. micrantha" was limited to Africa. Ernest Akamine (1947) found that there were no apparent dormancy mechanisms operating in the seeds, which germinated freely 135 days after being expelled from parent plants. Flower production can begin as early as 40 days after germination, with seed development beginning