Snow Geese

Snow geese are native to North America, breading in their summer habitat north of the tree line in Alaska, Canada and Greenland. The species is divided into two subspecies, the lesser snow goose (Chen caerulescens caerulescens) and the greater snow goose (Chen caerulescens atlanticus), with the lesser subspecies exhibiting two coloring morphs, snow or white and gray/blue or blue. The greater snow goose breeds in northeastern Canada and is occasionally seen in this area during winter migrations. The lesser snow goose is resident in Alaska and western Canada and migrates to southern Canada, the western US and Mexico.

Snow Geese in flight

It was once thought that the two plumage morphs or coloring were separate subspecies. Since birds of both plumages interbreed and are found together, the coloring is now considered to be of the same subspecies. The darker coloring is based on a dominant gene, and the white phase is based on recessive genes. It has been observed that young birds most often select mates with the same coloring as their parents, with the offspring of mixed plumage mating pairs not being particular as to the plumage of their mates. Seen in this area in the winter, greater snow geese have a shorter neck, a stockier body and are slightly smaller than the resident Canada geese most often seen in Frederick County. Greater snow geese are predominantly white in color, with black wing tips and rarely exhibit the gray/blue coloring. Both the lesser and greater snow geese have similar mating and nesting instincts.

Young female snow geese return in the summer of their second year to the location in which they were hatched to form long-term mating pairs, with mating generally occurring late spring of their 3rd year. The females typically build their nests in a depression in the ground, line it with plant matter and lay a clutch of 3 to 5 eggs which hatch in about 3 ½ weeks. The male helps protect the nest while the female is incubating the eggs. Within a day or 2 of hatching, young snow goslings are able to regulate their body temperature and leave the nest to hunt food on their own, under the protection of both parents. Growing rapidly, young snow geese are able to fly about a month and a half after hatching, although the young stay with their parents for 2 to 3 years when their own family units are started. Snow geese are mainly vegetarian, eating plant matter and grubbing for tubers and roots. Food passes rapidly through a snow goose digestive tract, in less than 2 hours, with resulting high rates of feces deposition, similar to that from Canada goose populations.

A combination of increased agriculture with rich sources of field grains along with prohibitions against hunting helped snow goose populations increase exponentially over the last 40 years from depleted levels a century ago. Areas of the tundra are stripped of vegetation by the large populations of snow geese, affecting their own and other species habitats including that of many nesting shorebirds. In some Arctic areas, survival of pre-flight goslings has become poor as a result of the absence of vegetation. Hunting snow geese in the US and Canada was reestablished to help control populations. Natural nest predators include Arctic foxes, northern sea birds, as well as other animal predators including bears and wolves. Adults have few natural enemies, and have been observed to have a life span of over 20 years.

Article by FCFCDB

Nature Notes for 1/18/2015