Small blue-gray falcon (Falco columbarius, family Falconidae), with a narrowly white-banded tail, found at high latitudes in Canada, the western U.S. south to Colorado, the British Isles, Scandinavia, and Iceland. Most migrate to just south of the breeding range, but some go as far as northern South America. The merlin inhabits wet, open country or conifer and birch woods. It usually lays its eggs on the ground in bushes, but may occupy an old rook or magpie nest in a tree. An aggressive hunter, it was once much used in falconry.