The dusky seaside sparrow (Ammospiza maritima nigrescens) was a non-migratory subspecies of the seaside sparrow, found in Florida in the natural salt marshes of Merritt Island and along the St. Johns River. Discovered in 1872 by Charles Johnson Maynard, it was distinguished from other seaside sparrows by its dark coloration and distinct song. From the 1940s onwards, the dusky seaside sparrow population declined and eventually went extinct. This was the result of human activity in the area including pesticides and flooding applied to reduce mosquito populations, industrial expansion, and highway construction. The last definite known individual died on Discovery Island in Walt Disney World in 1987, and the species was declared extinct in 1990.Photograph credit: P. W. Sykes, United States Fish and Wildlife Service