SpoilerBird list:
Centipedes, Alligators, Bald Eagles, Penguins, Chicken, Spiders, Crows, Peacocks, Owls, Tyrannosauruses, Blue whales, Squid, kangaroo, gorillas, turtles, octopuses, roses, sunflowers, trilobites, crabs, lions, tigers, wolves, giant pandas, grizzly bears, mammoths, hornets, flying fish, snails, dragons, chameleons, hammerhead sharks,


Some ____ are birds:
Birds, Passerines, flightless birds, reptiles, primates, strict-herbivores, insects, angiosperms, monkeys, beetles, extinct organisms, fish, fictional creatures, beetles with horns or pincers,

Not birds:
Humans, Snakes, Bees, Rotifers, Cockroaches, Worms, Annelids, Shrimp, Crocodiles, Gharials, Caimans, Ants, Canaries, Cassowaries, Emus, Kiwis, Vultures, Herons, Ducks, Sparrows, Doves, Seagulls, Sperm Whales, Platypuses, ratites, kakapos, Elephants, unicellular organisms, all marsupials except kangaroos, venus fly traps, sea turtles, all fungi except mushrooms, pacmen, termites, toads, hermit crabs, slugs, swans, eels, unicorns, Anomalocarises, domesticated animals except chickens, pokemon, dolphins, hummingbirds, red pandas, all canines except for wolves, all felines except lions or tigers, all extinct vertebrates besides mammoths and tyrannosauruses (probably), all plants except some angiosperms, rodents, all bears except grizzly bears and pandas, all wasps that are not hornets, griffons, aquatic fictional creatures, trees, all sharks except hammerheads, lizards that are not chameleons, mosquitoes, butterflies

There are 64 total types of things that are birds.

"Zoofights" while an extremely good guess are not birds.
Organisms who have never been represented in drawings are not birds.
Ghosts are not organisms so they are not birds
Some non human animals with sapience, maybe are birds
The organisms that share a taxonomical trait that is exclusive to organisms that are birds but is not simply a listing of the names of organisms that are birds are not birds.
Creatures that have not represented groups or individuals in a tournament bracket are birds.
Birds are not things that would make awesome names for sports teams.
Birds are not things which are depicted in art as having pointy teeth.
Birds are not organisms entered into a tournament bracket.
Birds are not creatures referenced in a specific piece of fictional literature.
Birds are not creatures referenced in a specific webcomic.
Birds are not creatures referenced in a specific film.
Birds are not creatures referenced in a specific TV series.
Birds are not creatures referenced in Animal Crossing.

SpoilerWHAT'S A VIDEOGAME WITH SNAILS?