Over the past century, a total of 434 bird species have been documented in the state, including five extinct, 11 provisional, and four extirpated species. However, not each of these species is reported in Missouri every year. Over the past decade, an average of 323 species are reported annually in Missouri. For a printable copy of Missouri's current online annotated bird checklist, click here. Some birds live in Missouri year-round, while others only show up for brief "stopover" periods to fuel up during migration. These stopover migrants spend either the winter or the summer in Missouri. Some migrants breed here in the summer, but spend their winters elsewhere. On rare occasion, a bird might show up in the state that would otherwise never been seen in Missouri for any reason. These "casual" or "accidental" birds usually attract flocks of birders eager to check the rarity off their lists.