The seasons of the year greatly influence the lives of birds. All birds must cope with weather, changes in food sources, and the stresses of breeding and nesting. In the spring, when the days begin to lengthen, the urge to mate and nest is triggered. Plumages brighten, migration begins for many species, mates must be found and nests built. Summertime is the season of busy days of feeding and caring for young. Soon it will be time for the long fall migration southward. When winter arrives, birds are ready to rest and rejuvenate for the time when the cycle begins again.
Range maps use colors to delineate the summer breeding areas and the wintering grounds. In the map shown here, red indicates summer, blue indicates winter, and purple the year-round range. This map shows the range of the White-crowned Sparrow.
Summer is the breeding season, when males and females mate, nest, and raise broods of chicks. The Chipping Sparrow (right) is a common North American breeding bird.
Most male birds wear their brightest plumage in the breeding and nesting season. This male Indigo Bunting (left) will molt its deep blue feathers and replace them with brown plumage as the season winds down.
Many birds go south when winter arrives, but some birds are permanent residents. This means that they have adapted to spend all seasons in the same place. The Cactus Wren is a permanent resident of the Arizona desert.
With the coming of winter, finding enough to eat becomes a problem for small birds. The Snow Bunting (right) scratches through deep snow for food.
Protecton from Predators
While most birds acquire their brightest plumage in spring, some have adapted to blend into their winter environment. The snowy White-tailed Ptarmigan (left) illustrates how plumage can act as protection from predators.
MIGRATION - SPRING AND FALL
During fall migration, many birds lose their bright plumage of spring and acquire a drab, less noticeable look. The Bay-breasted Warbler (right) is a typical confusing fall warbler.
To travel long distances for migration, many species, such as these Canada Geese, fly in formation to reduce air resistance and thereby conserve energy.
The handsome Eastern Phoebe (right) is among the first migratory birds to return north in the spring. Phoebes annually make their migratory journey from the southern United States and Mexico.