Their breeding habitat is coniferous or mixed forest areas throughout North America. In otherwise optimal conditions they also utilize other habitat, but at the southern margin of its range it can only persist in its favorite habitat. Northern birds migrate further south, arriving in their winter quarters between mid-September and November and leaving to breed from mid-March onwards, with almost all of them gone by the end of April or so. Many populations are permanent residents or altitudinal migrants, while in cold years they may choose to stay in their winter range and breed there. For example, in the Sierra Nevada of eastern California, "J. hymealis" populations will migrate to winter ranges lower than their summer range. In winter, juncos are familiar in and around towns, and in many places are the most common birds at feeders. The slate-colored dark-eyed junco is a rare vagrant to western Europe and may successfully winter in Great Britain, usually in domestic gardens.