The Canada goose was first introduced to England in the 17th Century to grace the waterfowl collections of wealthy individuals.

BBC: Windermere's 'polluting' Canada geese to be culled

The idea is that while a smaller sparrow isn't usually much concern, a larger hawk or Canada goose would be a problem when colliding with planes.

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Dr Fleischer's tree also suggests it may be time to abandon the Canada goose as a distinct species, and elevate its many subspecies one rung up the taxonomic ladder.

ECONOMIST: Feathers are flying in the world of bird classification