This list of birds of Missouri includes species documented in the U.S. state of Missouri and accepted by the Missouri Birding Society (MBS). As of July 2021, there are 437 species included in the official list. Of them, 54 are classed as accidental, 31 are classed as casual, 11 are classed as provisional (see below), seven have been introduced to North America, four are extinct and one might be, and three have been extirpated. This list is presented in the taxonomic sequence of the Check-list of North and Middle American Birds, 7th edition through the 62nd Supplement, published by the American Ornithological Society (AOS). Common and scientific names are also those of the Check-list, except that the common names of families are from the Clements taxonomy because the AOS list does not include them. Unless otherwise noted, all species listed below are considered to occur regularly in Missouri as permanent residents, summer or winter visitors, or migrants. The following codes are used to annotate some species: (A) Accidental - "1-4 records; occasionally observed" per the ASM (C) Casual - "5-15 records; occasionally observed" per the ASM (I) Introduced - Species established in North America as a result of human action (E) Extinct - a recent species that no longer exists (Ex) Extirpated - a species no longer found in Missouri but which continues to exist elsewhere (P) Provisional - "one or more records that meet acceptance criteria, but either (a) no definitive state record (i.e., specimen, diagnostic photograph or audio, or multiple acceptable documentations); or (b) provenance uncertain" per the ASM Ducks, geese, and waterfowl Order: AnseriformesFamily: Anatidae The family Anatidae includes the ducks and most duck-like waterfowl, such as geese and swans. These birds are adapted to an aquatic existence with webbed feet, bills which are flattened to a greater or lesser extent, and feathers that are excellent at shedding water due to special oils. Black-bellied whistling-duck, Dendrocygna autumnalis Fulvous whistling-duck, Dendrocygna bicolor Snow goose, Anser caerulescens Ross's goose, Anser rossii Greater white-fronted goose, Anser albifrons Brant, Branta bernicla (C) Barnacle goose, Branta leucopsis (P) (provenance uncertain) Cackling goose, Branta hutchinsii Canada goose, Branta canadensis Mute swan, Cygnus olor (I) Trumpeter swan, Cygnus buccinator Tundra swan, Cygnus columbianus Wood duck, Aix sponsa Garganey, Spatula querquedula (A) Blue-winged teal, Spatula discors Cinnamon teal, Spatula cyanoptera Northern shoveler, Spatula clypeata Gadwall, Mareca strepera Eurasian wigeon, Mareca penelope (C) American wigeon, Mareca