European starling is an aggressive omnivore that causes agricultural damage in the US.
Rose-ringed parakeet
The rose-ringed parakeet is a popular pet in Europe, but is a pest in Western Australia and causes agricultural damage.
Red-billed leiothrix
The red-billed leiothrix is a highly adaptable species native to Southeast Asia, which has spread to Europe, Japan, Hawaii, and Italy.
Ruddy duck
The ruddy duck poses a threat to the survival of the white-headed duck due to its hybridization with the ruddy duck.
Shiny cowbird
The shiny cowbird is a brood parasite, relying on another bird to incubate its eggs and rear its chicks. This negatively affects native bird species in the Caribbean and North America.