With the change of season and the return of the food chain in the Northern Hemisphere each spring, an enormous breeding and feeding range opens up. Hummingbirds have both themselves and their young to feed in summertime. In the north, where there's less competition for food and habitat, hummingbirds raise their young until the season changes and weather turns cold. In winter, Central America provides a safe refuge for many birds from the northern regions. Habitat there is critical to survival for the billions of northern birds who winter there as well as the year-round residents.