D e s e r t E x p o s u r e
December 2009
Flight of the Snow Goose
These snowbirds don't need an RV for their annual migration to New Mexico and points south.
Story and photos by Jay W. Sharp
The Lesser Snow Goose — one of the most abundant, wide ranging, gregarious and noisy water birds in North America — stages a showy pageant in the Southwest and central United States every year through the fall and winter seasons.
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Snow Geese in early
morning flight, looking almost like what George Bird Grinnell called "so
many snowflakes." |
"The spectacle of a flock of these white geese flying," said naturalist George Bird Grinnell in his 1901 book American Duck Shooting, "is a very beautiful one. Sometimes they perform remarkable evolutions on the wing, and if seen at a distance look like so many snowflakes being hurled hither and thither by the wind."
Lesser Snow Geese usually occur in a white phase, but some may also occur in a blue phasea rare trait called "plumage dimorphism," according to naturalist Charles Gorecki, writing for the Nodak Outdoors Internet site. In either phase, males and females resemble each other closely.
The Lesser Snow Goose, weighing about five to six pounds, has a length of approximately two and a half feet and a wingspan of roughly three feet. The male is slightly larger than the female. In the white phase, the mature bird has snowy white plumage overall, but with black wing tips. In the blue phase, the mature bird has dark gray to bluish plumage on the back, breast and trailing wing feathers, pale to dark plumage on the belly and leading wing feathers, and white feathers on the head. In either phase, the Lesser Snow Goose has a pinkish orange bill and feet and a wedge-shaped head, and it has serrated edges along the sides of the bill, suggesting a sardonic grin.
The Lesser Snow Goose (Chen caerulescens caerulescens) has two close relatives — the somewhat larger Greater Snow Goose (Chen caerulescensa atlantica), which generally occupies a range farther north and east, and the smaller Ross's Goose (Chen rossii), which shares much of the Lesser Snow Goose's range. Where their ranges overlap, the Lesser Snow Goose and the Ross's Goose may interbreed, producing a hybrid that is intermediate in size.
Distribution and Migration Habits
The Lesser Snow Goose, with a growing population that now numbers well into the millions, nests in dense colonies in the northwestern corner of Greenland, the northern reaches of Canada, the northern edge of Alaska, and the primal landscape of far eastern Siberia's Wrangle Island. Many nest well above the Arctic Circle.
Anticipating the coming of fall, Lesser Snow Goose breeding populations congregate at staging areas in flocks of tens of thousands, preparing for their annual journeys southward. Those that gather near the shores of Alaska's northern coast and near the Mackenzie River delta on the Northwest Territories' coast will head southward, down the Pacific and Central flyways, for the southwestern United States and northern Mexico. They will take up winter residence primarily in south-central New Mexico's Rio Grande wetlands (especially the Bosque del Apache National Wildlife Refuge), California's central valleys, the lower Colorado River, Mexico's northern Chihuahuan desert river basins and playa wetlands, and Mexico's Gulf of California shorelines.
In early spring, the Lesser Snow Goose populations again gather in large numbers at staging sites, preparing to reverse their fall route in their return to their nesting areas.
According to authorities Thomas B. Mowbray, Fred Cooke and Barbara Ganter, the Lesser Snow Goose follows well-defined spring and fall migration corridors. Its journey is "characterized as a combination of long stopovers with rapid and distant flights between areas, flying at high altitudes."
Habitat and Diet
In the western, midcontinent and easternmost nesting grounds, Lesser Snow Goose breeding populations typically prefer river mouths, river islands, lake shorelines and tundra ponds north of the Arctic Circle. Using their serrated bills and tough serrated tongues as tools, they grub on roots, underground stems and aquatic plant shoots.
In their Southwest and Mexican wintering ranges, the Lesser Snow Goose flocks favor riverine wetlands (like the Bosque del Apache), valleys, impoundments and desert playa lakes. They feed, often in large gatherings, on fresh shoots of aquatic plants and scavenge in agricultural fields for waste grain.
Behavior and Life Cycle
During its second winter or second spring migration, say Mowbray, Cooke and Ganter, the Lesser Snow Goose selects a mate and forges a lifelong bond. In courtship, the male inflates its body, walks tall like John Wayne, and follows the female. He may compete with another male for her attention. She plays coy, pretending to ignore him before she accepts his overtures. Once bonded, according to Gorecki, the female takes her male home, to her colony's breeding grounds. He forsakes his own colony for the rest of his life.
Getting Goosed
The Lesser Snow Goose may cover 1,500 to 2,000 miles in its spring and fall migrations, flying at speeds of more than 40 miles per hour and elevations of as much as 7,500 to 8,000 feet. In migratory journeys, a flock, in a continual chorus of calls, typically flies in undulating, long diagonal lines or U formations, giving rise to the colloquial name of "wavies." The Lesser Snow Goose population has increased dramatically — to perhaps as many as five or six million, according to some estimates — over the past few decades, probably because global warming and earlier melting snows in the breeding areas have opened new nesting grounds and changing agricultural practices in the wintering areas have provided increased food sources. Moreover, the birds have found more winter sanctuary in the increased number of wildlife refuges. In some areas, the Lesser Snow Goose, with its growing abundance, has overwhelmed many of its food plants, both in its summer and winter grounds. If the population continues to increase, Gorecki warned, the birds "will destroy all of their suitable nesting habitat and 10s of millions of fledgling geese will starve to death" and this will lead to "an eventual population collapse." |
Upon reaching the breeding grounds, a pair begins to flirt, with the male bobbing his head and cocking his tail and the female dipping her head and bill. Every day, early in the morning, the pair will mate, then celebrate the occasion by stretching, flapping, preening, bathing and vocalizing.
When egg-laying time arrives, the pair joins a large colony of nesting kin, including perhaps as many as several thousand other Lesser Snow Goose couples within a square-mile range. The female, in council with her mate, selects a nesting site. She prepares a "scrape" several feet in diameter on the surface of the ground, preferably in well-drained sandy soil near sheltering plants or rocks. As she lays her eggs, usually numbering two to six, she lines her nest with plant material and downy feathers. She incubates her clutch — her only one for the season — with her mate usually standing nearby, vigilantly overseeing the proceedings and shooing away would-be predators.
The chicks hatch within three to four weeks, and they may leave the nest with their parents as soon as the following day, ready to learn the art of being a Lesser Snow Goose. They must grow rapidly if they are to accompany their parents on the long fall migration. The family may remain together until the following breeding season. According to Lisa Drew and Chris Madson, writing for National Wildlife Magazine, the Lesser Snow Goose commonly lives well into its teens and occasionally for 20 years or more.
Life's Hazards
The Lesser Snow Goose is most vulnerable during nesting and hatching, when various predators may steal eggs or attack the goslings. Adult birds may also fall to various predators, however. Several years ago, at the Bosque del Apache, I saw an adult Lesser Snow Goose serve as a meal for a Golden Eagle.
The male and female both mount a vigorous defense of their nest and goslings, attacking would-be predators with their feathers ruffled, wings spread and necks extended. They sound the alarm to the flock, which may take flight in an explosion of white and bluish gray.
If you want to make a pair of Lesser Snow Geese really mad, try laying an egg in their nest. You may find yourself grabbed at the throat by that serrated bill with a sardonic smile and flogged in the face by three feet of wings. Sometimes, Lesser Snow Geese flight to the death over such an issue.
Jay W. Sharp is a Las Cruces author who is a regular contributor to DesertUSA, an Internet magazine, and who is the author of Texas Unexplained.