Labrador Duck: never common. The breeding range unknown (Atlantic); wintered to New Jersey. Between 1850-1875 it disappeared, causes unknown. Probably not over hunted, not common in Eastern bird markets; it was lousy eating anyway so it may have gone extinct naturally.
Passenger Pigeon: darkened skies--1 flock, estimated to contain a million birds, took 3 days to pass! They were good to eat and oily. They were highly gregarious and were slaughtered by millions, but extinction may have been due to their COMPACT BREEDING COLONIES--breeders could be shot out and young taken. The tide of their extinction went like this: 1850- none in NE; 1855 Ohio and Indiana; 1885 Great Lakes; 1894 last nest; 1899 last wild; 1914 last zoo bird (Martha in the Cincinnati Zoo)
Carolina Parakeet-a mystery bird, only North American native parrot (unless you count the Thick-billed Parrot which is accidental in Arizaona). Always relatively uncommon, it was mostly gone by 1900s--the last sighting was in 1938. It occuppied the same habitat as Ivory-bill but disappeared BEFORE lumbering. This bird was an agricultural pest: orchards and corn, so shot at. Its fatal flaw seems to be that it stuck around dead flock members. Or perhaps it succumbed to avian diseases brought to the New World by European settlers.
Ivory-billed Woodpecker? It ate grubs in dead trees. May still exist in the Big Thicket of eastern Texas, or the Louisiana or Arkansas swamps. May also exist in Cuba. A victim of habitat destruction, the species was rediscovered in 2005 in Arkansas.