Lappet-faced vulture, a species of Old World vulture native to Africa. It can compete some native turkey vultures, but isn't impacting native turkey vultures (yet).
Griffon vulture, a species of Old World vulture native to Africa and Eurasia. It can compete some native turkey vultures, but isn't severely impacting native turkey vultures (yet).
King vulture, a species of New World vulture native to South America. It can compete some native turkey vultures for food, but isn't severely impacting native turkey vultures (yet).
Western capercaillie, a species of gamebird native to Eurasia. It can compete native grouse for food and territory and can charge at humans.
Ocellated turkey, a species of turkey native to Mexico. It can compete with introduced wild turkeys and native quails for food and territories.
Roseate spoonbill, a species of wading bird native to South and Central America, as well as the Gulf Coast of the United States. They can compete with some native shorebirds for food.
Greater flamingo, a species of wading bird native to Africa. They can compete with some native shorebirds for food.
Andean cock-of-the-rock, a species of songbird native to South America. It can outcompete some native small songbirds.
Screaming piha, a species of songbird native to South America. This noisy songbird can outcompete some native songbirds.
Capuchinbird, a species of songbird native to South America. It can outcompete native songbirds.
Long-wattled umbrellabird, a species of large songbird native to South America. It can outcompete somenative songbirds.
Montezuma oropendola, a species of songbird native to Central and South America. It can outcompete some native songbirds.
Magnificent riflebird, a songbird native to New Guinea. It can outcompete some native songbirds.
Superb bird-of-paradise, a species of songbird native to New Guinea. It can outcompete some native songbirds.
Greater bird-of-paradise, a species of songbird native to New Guinea. It can outcompete some native songbirds.
Great bowerbird, a species of songbird native to Australia. It can outcompete some native songbirds.
Laughing kookaburra, a species of kingfisher native to Australia. It can outcompete some native fish-eating animals for food.
Great hornbill, a species of hornbill native to Asia. It can outcompete some native flying herbivorous birds.
Wreathed hornbill, a species of hornbill native to Asia. It can outcompete some native flying herbivorous birds.
Rhinoceros hornbill, a species of hornbill native to Southeast Asia. It can outcompete some native flying herbivorous birds.
Knobbed hornbill, a species of hornbill native to Indonesia. It can outcompete some native flying herbivorous birds.
California tree hornbill, a hybrid between an African grey hornbill and a red-billed hornbill. It can outcompete some native songbirds.
California ground hornbill, a hybrid between a southern ground hornbill and an Abyssinian ground hornbill. This species can outcompete some native populations of egrets.
Toco toucan, a species of toucan native to South America. It can outcompete some native flying herbivorous birds.
Keel-billed toucan, a species of toucan native to South America. It can outcompete some native flying herbivorous birds.
Resplendent quetzal, a species of quetzal native to Central America. It can outcompete some native songbirds.
Society finch, a domesticated finch species not found anywhere else in the wild. It can outcompete some native songbirds.
Black-rumped waxbill, a species of finch native to Africa. It can outcompete some native songbirds.
Grey go-away bird, a species of go-away bird native to Africa. It can outcompete some native flying herbivorous birds.
Zebra finch, a species of finch native to Australia. It can outcompete some native songbirds.
Java finch (often called Java sparrow), a species of finch native to Southeast Asia. It can outcompete some native songbirds.
Gouldian finch, a species of finch native to Australia. It can outcompete some native songbirds.
Red-billed quelea, a species of finch native to Africa. It can outcompete some native songbirds and destroy many crops.
Domestic canary, a domesticated songbird found nowhere else in the wild on Earth. It can outcompete some native songbirds.
White-faced whistling duck, a species of duck native to Africa and South America. It can outcompete native ducks such as mallards.
Wild swan goose, a species of wild goose native to Asia. It can outcompete some populations of native geese.
Emperor goose, a species of wild goose native to Siberia and Alaska. It can outcompete some populations of native geese.
Bar-headed goose, a species of wild goose native to Asia. It can outcompete some populations of native geese.
Egyptian goose, a species of wild goose native to Africa. It can outcompete some populations of native geese.
Marabou stork, a species of stork native to Africa. It can outcompete some native populations of heron.
White stork, a species of stork native to Europe and Africa. It can outcompete some native populations of heron.
California crowned crane, a hybrid between a grey crowned crane and a black crowned crane. It can outcompete some populations of native egrets and some other herons.
Superb lyrebird, a species of ground bird native to Australia. It can outcompete some native ground-dwelling songbirds and its foraging behavior can change structures on many California's forest's floors, threatening some native species and spreading non-native eucalyptus trees.
Eastern spinebill, a species of honeycreeper native to Australia. It can outcompete some native populations of hummingbirds due to a similar lifestyle and nectar being part of its diet.
Vampire ground finch, a species of small bird native to the Galápagos Islands. It was genetically modified by some pet owners to tolerate the colder and hotter temperatures, wetter and drier climates, as well as North American predators (native and non-native), and has developed taste for other sources of blood, including that of other birds as well as mammals (including humans).
Rufous motmot, a species of near-passerine bird native to Central and South America. It can outcompete some native omnivorous birds such as some populations of American crows.
European roller, a species of near-passerine bird native to Europe, it can outcompete some native insectivorous birds and severely impact populations of some native arthropods.
Swallow-tailed bee-eater, a species of bee-eater native to Africa, it can outcompete some native insectivorous birds.
Southern carmine bee-eater, a species of bee-eater native to Africa, it can outcompete native insectivorous birds and its nesting behavior causes erosion to cliffs, eventually causing these eroded cliffs to crumble, destroying man-made structures bellow.
European bee-eater, a species of bee-eater native to Europe, it can outcompete some native insectivorous birds for food.
Scarlet macaw, a species of parrot from Central and South America. The feral scarlet macaws in California are descended from escaped/released pet scarlet macaws and are somehow flourishing, even in Northern California, despite how cold Northern California can get.
Blue-and-yellow macaw, a species of parrot from Central and South America. The feral blue-and-yellow macaws in California are descended from escaped/released pet blue-and-yellow macaws and are somehow flourishing, even in Northern California, despite how cold Northern California can get.
Military macaw, a species of parrot from Central and South America. The feral military macaws in California are descended from escaped/released pet military macaws and are somehow flourishing, even in Northern California, despite how cold Northern California can get.
Hyacinth macaw, a species of parrot from Central and South America. The feral hyacinth macaws in California are descended from escaped/released pet hyacinth macaws and are somehow flourishing, even in Northern California, despite how cold Northern California can get.
Spix's macaw, a species of parrot from Central and South America. The feral Spix's macaws in California are descended from escaped/released pet Spix's macaws and are somehow flourishing, even in Northern California, despite how cold Northern California can get.
African grey parrot, a species of parrot from Africa. The feral African grey parrots in California are descended from escaped/released pet African grey parrot and are somehow flourishing, even in Northern California, despite how cold Northern California can get.
Sulphur-crested cockatoo, a species of parrot from Australia. The feral sulphur-crested cockatoos in California are descended from escaped/released pet sulphur-crested cockatoos and are somehow flourishing, even in Northern California, despite how cold Northern California can get.
Palm cockatoo, a species of parrot from Australia. The feral palm cockatoos in California are descended from escaped/released pet palm and are somehow flourishing, even in Northern California, despite how cold Northern California can get. Palm cockatoos in California severely damage some native and non-native palm trees, through foraging and/or roosting, making them agriculture pests. However, despite being shot down in California, their numbers are increasing due to their fast reproduction due to genetic engineering by historic pet breeders before lawmakers made this species illegal to keep in California..
Cockatiel, a species of parrot from Australia. The feral cockatiels in California are descended from escaped/released pet cockatiels and are somehow flourishing, even in Northern California, despite how cold Northern California can get.