For generations of Minnesota waterfowlers and birders, there was nothing easier to identify, on the ground or in the air. Smallish geese, white with black wingtips, high-pitched call? Obviously snow geese. Lesser snow geese, to be exact. The only complication was an occasional darker bird in the flock, but when taxonomists decided that these "blue" geese were just a color phase of the snow goose, this source of potential confusion disappeared.

Then, in the early 1990s, a few sharp-eyed observers began to report different birds in the flocks of snows. These were even smaller than the snow geese, not much bigger than a mallard. Their heads were smaller, their bills shorter, and they lacked the "grinning patch" that is so obvious on the snow goose bill.

They were Ross's geese, a species that, until the last decades of the 20th century, was found almost entirely in the Rocky Mountain West on a migration route between California's Central Valley and the tundra of the central Arctic.

Bob Dunlap, a Department of Natural Resources zoologist, helps keep records of birds in Minnesota.

"A few decades ago, the species was still considered 'casual' in the state, that being less than 9 out of 10 years it was detected," he says. "That was probably the late '80s. By the late '90s, you started seeing more of them, and in the 2000s, a lot more frequent reports. Now they're annual, and they're expected in pretty much any big flock of snow geese you see."

In the mid-1930s, experts estimated the world's population of Ross's geese at between 3,000 and 6,000, all of which wintered in California and migrated north and east into the wilderness along the shores of Queen Maude Gulf. Their nesting colony in this remote corner of the continent wasn't known to science until a Hudson's Bay Company employee posted on an island in the Arctic Ocean reported it in 1938. The U.S. hunting season for the species was closed in 1931 to help protect the remaining birds, but the species didn't rebound until the 1940s, when new cultivars more than doubled the acreage of rice planted in California. With the increase in available waste grain and flooded rice fields, the Ross's goose began a startling recovery.

Beginning in 1957, the numbers of Ross's geese in California's Central Valley began a precipitous rise, quadrupling in a single decade. Since 2007, the estimate of Ross's geese in the Perry River area of north-central Canada, their largest nesting colony, has hovered around 700,000 birds. As their population has risen, the geese have established new nesting colonies in the far north, and their migrations have moved steadily eastward, following growing flocks of lesser snow geese to wintering areas across the Southwest and as far east as the Gulf Coast of western Louisiana and the rice fields of Arkansas.

Which is why the Ross's goose, historically a bird of California and the Rocky Mountain West, has come to Minnesota. Oddly enough, the chances of seeing a big flock of white geese in Minnesota have actually declined a little as the populations of both Ross's geese and lesser snows have increased. Steve Cordts, DNR waterfowl specialist in Bemidji, says that white geese used to show up regularly in the southeastern corner of the state. These days, he says they're more common along the western border, but even there, harvest of white geese during the spring season is low, from a few hundred to a few thousand a year. Ross's geese are rare in the hunter's bag.

No one is sure why the migration routes through Minnesota have changed. Some of the shift may be due to the rapid growth of snow goose nesting colonies in the central Arctic, far to the west of the traditional snow goose gatherings along the western shore of Hudson's Bay. When the Ross's goose breeding grounds were discovered on the Perry River, there were almost no snow geese nesting there; today, both species are abundant in the area.

Changes in farming practices may also have played a role. Ross's geese and lesser snows have always stopped to feed in small grain fields on their way north, and in the last 20 years, they've found a new source of food in the farmland of southern Canada, a group of crops collectively referred to as pulse. The term includes dry peas and beans, chickpeas, and lentils, all high in protein and all excellent goose food. The direct routes to these fields from wintering areas in Arkansas, Louisiana, and Texas lead along the western border of Minnesota, the most likely place to see Ross's geese in the state, especially in the spring.

The recovery of the Ross's goose is one of the most remarkable stories in the history of American wildlife conservation, rivaling the renaissance of the trumpeter swan, the wood duck, even the prairie chicken in its drama. If the goose has enjoyed less prominence than these other birds, it may be because of its close resemblance to its larger cousin, the lesser snow goose. Largely unrecognized, the Ross's goose is nevertheless a living monument to the continental effort to protect American waterfowl.

Wherever they go, the white geese make an impression, the Vs incandescent against the sky, the flocks dropping into their resting places like cyclones of snow, and, always, the tenor chorus blurring into a roar like the north wind, a sound as wild as the tundra that gives it birth. Among these far travelers are the representatives of a species that was almost given up for dead, the smallest of its kind but, arguably, the toughest— the Ross's goose, bearing witness to the hope of another spring.