Anser caerulescens

Geographic Range

Chen caerulescens have quite an expansive geographical range. They leave their wintering grounds in March and head north over the New England states. They rest between the first week in April and the end of May in the St. Lawrence River area. They then continue northward over central Quebec, Canada to their destination in the northeast artic. The breeding grounds cover the area from northern Baffin Island, west to Bathurst Island, north to Alert on Ellesmere Island, and east to northwest Greenland. The southwest coast of Bylot is the location of the main nesting colony. They leave their breeding grounds in September. They begin to arrive at the St. Lawrence River area in October and stay until early November when they continue to their American wintering grounds(Heyland, 2000). Their main wintering grounds are along the gulf coast of Louisiana and Texas between the Mississippi delta and Corpus Christi, Texas. However, in recent years colonies have been seen in Missouri, Illinois, Kansas, Oklahoma, Nebraska, and Iowa. Smaller numbers are found in eastern Mexico and southern New Mexico (Belrose, 1942).

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

The breeding grounds of Chen caerulescens consist of low grassy tundra with flat basins within 10 km of lakes, rivers, flood plains, or seas. Some choose rockier terrain near grassy wet tundra and flat marshy areas protected from the north by mountains. Overall they prefer coastal lagoons, marshes, tidal flats, and estuaries, but have been known to take advantage of prairies and agricultural lands.

• Habitat Regions
• temperate temperate
• polar polar
• terrestrial terrestrial

• Terrestrial Biomes
• tundra tundra
• savanna or grassland savanna or grassland

• Wetlands
• marsh marsh

• Other Habitat Features
• agricultural agricultural
• estuarine estuarine

Physical Description

Chen caerulescens stand 63.5 to 78.7 cm tall (and average 70 cm in length) with wing lengths varying from 400 to 450 mm. They weigh from 2 to 3 kg. Males and females are similar in appearance although males are usually larger. There are two phases seen in Chen caerulescens called the "snow" phase and the "blue" phase. In the adult "snow" phase the body is a snowy white with black wing tips. They have red feet and legs, a pink bill, and a black "grin patch" (the black patch of skin that surrounds the base of the bill, which resembles a smile). The adult blue phase geese have the same feet, legs, bill, and grin patch, but they have blue/gray bodies with black wing tips. They also have white necks and heads, and some white on the underside of their bellies. In the immature snow phase the body is a dirty white color with black wing tips and in the immature blue phase they are a slate gray with little or no white. In both immature phases they have red feet and legs but they are not as bright as the adult goose. It was once thought that the two different color phases were different species, but they are not. They interbreed with one another, and they are found together through out their geographical ranges. The colors are genetically controlled and when selecting mates they tend to choose a mate that resembles their parents. Individuals with a mixed set of parents will breed with either color phase.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry
• polymorphic polymorphic

• Sexual Dimorphism
• sexes alike
• male larger

Development

There are three stages of development in Chen caerulescens . There are the hatchlings and young, the juvenile non-breeders, and the adult breeders. The young grow rapidly and are fully fledged within forty-five days. They reach maturity in two years, which is when they usually pair up in a monogamous relationship with another Snow Goose. The pair begins to breed for the first time in June of the third year (Belrose 1976).

Reproduction

Chen caerulescens are monogamous and usually form long-term pair bonds.

• Mating System
• monogamous monogamous

Chen caerulescens actually mate with their monogamous partners during their migration back to the artic tundra. Nesting occurs in June; nesting colonies can number in the tens of thousands. The geese begin building nests approximately ten days after arriving at the nesting site. They usually make shallow depressions in the ground and line them with bits of dry vegetation and down from the mother. The female will lay one egg a day until she reaches a full clutch of about 3 to 5. The eggs are incubated for 23 to 25 days while the male guards the nest and the mother. Young fledge in 45 to 49 days. Females reach sexual maturity between 2 and 4 years. Snow geese tend to nest near snowy owls, which are believed to deter predators from coming to the nests.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
  • internal internal
• oviparous oviparous

Young snow geese are precocial and receive parental care from both the male and female parent.

• Parental Investment
• no parental involvement
• precocial precocial
• pre-fertilization
• pre-hatching/birth
  • protecting
• pre-weaning/fledging
  • provisioning
    • male
    • female

Lifespan/Longevity

The actual lifespan of Chen caerulescens is unknown, however, it is believed they have quite long lifespans. It was reported in one case that a goose was banded in 1957 and killed fifteen years later by a hunter. Annual mortality is between 25 to 50 percent and depends on age and breeding status.

Behavior

Chen caerulescens are migratory birds that travel all the way from the northeast of Canada to the Gulf of Mexico and back. They travel in large flocks made of many family units and fly during both night and day. They tend to return to the same nesting areas year after year. During nesting the Geese break up into monogamous pairs. Both parents guard the brood, but the female does most of the brooding of the young. When taking the broods away from nest site females tend to group together in family packs. The males are territorial toward other males, and the females toward other females (Belrose, 1976). They usually nest in colonies, but some nest individually. They have been seen nesting near snowy owl nests, which is likely a solution to predation. Their nesting success was much lower when snowy owls were absent, which lead scientists to believe that the owls, since they are predatory bird, were capable of keeping predators away from the nests (Tremblay et al., 1997).

• Key Behaviors
• flies
• motile motile
• migratory migratory
• territorial territorial
• social social
• colonial colonial

Home Range

We do not have information on home range for this species at this time.

Communication and Perception

Chen caerulescens are known for their loud squawking and honking but no real studies have been done to determine the meanings, if any, of their vocalizations.

• Communication Channels
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Chen caerulescens are herbivorous; they eat roots, leaves, grasses, and sedges. They have strong bills for digging up roots in thick mud. Their most common food source in the northern breeding grounds is American bulrush. As they migrate south they feed on the aquatic vegetation in wetlands and estuaries. They also forage in agricultural fields for wasted oats, corn and winter wheat. They eat tender shoots as they come up or feed on grass, weeds, and clover. In their Louisiana wintering grounds they feed on wild rice. Snow geese also need some sort of grit such as sand or shell fragments to aid in their digestion.

Foods eaten include: saltgrass, wild millet, spikeruch, feathergrass, panic grass, seashore paspalum, delta duckpatato, bulrush, cordgrass, cattail, ryegrass, wild rice, berries, aquatic plants and invertebrates, and agricultural crops.

• Primary Diet
• herbivore herbivore
  • folivore folivore

• Animal Foods
• insects

• Plant Foods
• leaves
• roots and tubers
• seeds, grains, and nuts
• fruit

Predation

Major predators include artic foxes ( Alopex lagopus ) and gull-like birds called jaegers (genus Stercorarius ). The biggest threat occurs during the first couple of weeks after the eggs are laid and then after hatching. The eggs and young chicks are vulnerable to these predators, but adults are generally safe. They have been seen nesting near snowy owl nests, which is likely a solution to predation. Their nesting success was much lower when snowy owls were absent, which lead scientists to believe that the owls, since they are predatory bird, were capable of keeping predators away from the nests (Tremblay et al., 1997).

Ecosystem Roles

Chen caerulescens are considered to be overabundant and as a result have been stripping their habitat of its vegetation.

Economic Importance for Humans: Positive

Because of their large numbers the snow geese are hunted, although there are restrictions in place in order to protect the species from over hunting.

• Positive Impacts
• food food

Economic Importance for Humans: Negative

In recent decades many snow geese have become agricultural pests. They sometimes opt for easy food supplies found in farm fields with tender shoots and wasted corn, wheat, and oats.

• Negative Impacts
• crop pest

Conservation Status

The population size of Chen caerulescens is increasing at an estimated rate of 130,000 birds per year. Periodic hunting seasons have been established to help curb the growing population. There are restrictions, however, that protect snow geese from overhunting and efforts have been made to protect critical habitat in Canada and the United States.

Additional Links

Encyclopedia of Life

Contributors

Alaine Camfield (editor), Animal Diversity Web.

Jessica Logue (author), Western Maryland College, Randall L. Morrison (editor), Western Maryland College.

References

Belrose, F. 1976. Ducks, Geese and Swans of North America . Harrisburg, PA: Stackpole Books.

Ehrlich, P., D. Dobkin, D. Wheye. 1988. The Birder's Handbook: A field guide to the natural history of North American birds . New York: Simon & Schuster Inc.

Frerichs, T. 1997. Lesser Snow Goose . Columbia, SD: U.S. Fish and Wildlife Service.

Hebert, P. 2002. "Snow Goose, Chen caerulescens" (On-line). Canada's Aquatic Environments. Accessed January 28, 2004 at http://www.aquatic.uoguelph.ca/birds/speciesacc/accounts/ducks/caerules/account.htm .

Heyland, J. 2000. "Canadian Wildlife Service. Greater Snow Goose" (On-line). Accessed April 9, 2002 at www.cws-scf.ec.gc.ca/hww-fap/greatsg/gsgoose.html .

Tremblay, J., G. Gauthier, D. LePage, A. Desrochers. 1997. Factors affecting nesting success in Greater Snow Geese: Effects of habitat and association with snowy owls. Wilson Bulletin , 109: 449.