Photograph courtesy Dave Menke/U.S. Fish and Wildlife Service
Snow geese are known for their white plumage, but many of them are actually darker, gray-brown birds known as blue geese. These birds were once though to be two separate species, but they have recently been found to be merely two different color morphs of the same bird. A single gene controls the color difference.
Snow geese are harbingers of the changing seasons. They fly south for the winter in huge, honking flocks that may appear as a "U" formation or simply as a large "snowstorm" of white birds. They spend the colder seasons in southern coastal marshes, bays, wet grasslands, and fields. Their diet is entirely vegetarian, consisting of grasses and grains, grazed from damp soils or even shallow water.
At winter's end, snow geese fly north to their breeding grounds on the Arctic tundra. Pairs mate for life, and produce two to six eggs each year in a shallow ground nest. Chicks can swim and eat on their own within 24 hours, but families remain together through the young's first winter. Families can be identified as groups during both the southern and northern migrations.
Read full here... http://animals.nationalgeographic.com/animals/birds/snow-goose/