Common bird species that can be observed in Westland Tai Poutini include the rockwren (Xenicus gilviventris), kereru (Hemiphaga novaeseelandiae), kea (Nestor notabilis), purple swamphen (Porphyrio melanotus), tomtit (Petroica macrocephala), tui (Prosthemadera novaeseelandiae), silvereye (Zosterops lateralis), fernbird (Bowdleria punctata), common chaffinch (Fringilla coelebs), welcome swallow (Hirundo neoxena), pied cormorant (Microcarbo melanoleucos), spur-winged plover (Vanellus spinosus), white-faced storm petrel (Pelagodroma marina dulciae/ maoriana), little pied shag (Phalacrocorax melanoleucos brevirostris), great cormorant (Phalacrocorax carbo), pied shag (Phalacrocorax varius varius), swamp harrier (Circus approximans gouldi), new zealand falcon (Falco novaeseelandiae), western weka (Gallirallus australis australis), and the grey warbler (Gerygone igata).
Some bird species are rare to see such as the threatened crested grebe (Podiceps cristatus), white heron (Ardea modesta, Ardea alba), blue duck (Hymenolaimus malacorhynchos), Fiordland crested penguin (Eudyptes pachyrhynchus), sooty shearwater (Puffinus griseus), Australasian bittern (Botaurus poiciloptilus), royal spoonbill (Platalea regia) as well as the rowi kiwi (Apteryx rowi) that is believed to have a remaining population of 400 to 500 birds. New Zealand fur seals (Arctocephalus forsteri) are regular visitors of the coastline.
Several freshwater fish species may be found in Westland's waters including inanga (Galaxias maculatus), shortjaw kokopu (Galaxias postvectis), short- and long-finned eels (Anguilla), crayfish (Paranephrops planifrons), mussels, cockle beds, mudcrabs, snails, flounder, kahawai and yellow-eyed mullet.
Introduced species are possums, red deer, chamois, thar, rabbits, brown trout, and quinnat salmon.