Chen rossii

The snow geese have arrived in northern Utah after traveling from their wintering grounds in Texas and other southern regions. Birders are enjoying them in the fields near Corinne.

Do not assume all of the geese in those fields are snow geese. Look closely at those "white" geese, and you will likely be rewarded by seeing a smaller white goose with a pink bill and black wingtips.

This is the Ross's goose. It is a miniature version of the more abundant snow goose. It breeds in the central Arctic and winters primarily in central California.

The Ross's goose has a smaller population than its larger cousin, the snow goose. But the Ross's population is growing.

They are a smaller species of goose, with a wing span of 22 to 25 inches. They weigh between 2 and 4 1/2 pounds.

They breed on the Arctic tundra, and the downy young are yellow or gray. Once mature, they show the characteristic white body with black primaries.

On rare occasions, a Ross's goose can be found in a dark morph phase, like the blue phase of its larger snow goose cousin. These morphs are believed to be hybrid offspring from Ross's and snow goose parings.

Ross's geese are expanding their range eastward. This expansion has led to increased hybridization with the snow goose.

Incubation duties are performed exclusively by the female, with her mate performing as a guard while she is on the nest. The eggs are covered with down whenever the female leaves the nest to keep the eggs warm and protect them from view of predators.

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* BILL FENIMORE is owner of the Layton Wild Bird Center (www.wildbird.com/layton).