A friend and fellow Grand Valley Audubon Society board member, Cary Atwood, told me about an influx of Rosy-Finches she has had in her yard. I couldn't refuse when she offered to write about them for me to share with everyone in this column. Her article follows:With a dusting of fresh snow a few days after New Year's, and the temperatures hovering in the single digits, a mass of birds numbering somewhere between 200-300 rain onto our patio and become a manic and ever-moving mob of seed-cracking machines as they devour every black oil sunflower seed in sight within minutes. These are not just your every day House Finch with a thick seed-cracking bill, but a very special winter visitor not often seen here in the Grand Valley: Rosy-Finches! With the many weeks of bitter cold, snow and valley inversion this winter, flocks of Rosy-Finches came visiting us at lower elevations, in an act termed vertical migration. This behavior of some species during the winter months is a move from high to low elevations to seek a sustainable food source. Their year-round home habitat is bare alpine tundra above tree line, nesting in loose colonies in rock crevices of cliffs and crags. If you are a summer or fall visitor to the tundra, you may be lucky enough to spot flocks of these finches as they forage for seeds as well as insects carried aloft by winds and dropped onto high altitude snowfields.The Rosy-Finch name connects them to their plumage colors: Black-Rosy for the black and silver grey of their heads, and the striking dark pink of their wing and belly. The Gray-crowned and Brown-capped also refer to their head color. Along with a golden brown body, they show a lovely deep pink on their wings and under parts. We were mesmerized by the feeding frenzy of this rare winter visitor, now inches from our windows. To feed our curiosity about these birds and observe their dramatic and more subtle differences, we kept spreading seed onto the patio. Within minutes, this massive flock would whirl, turn, land in a nearby tree and quickly drop to the seeds. Just as quickly, sensing some danger, real or imagined, they would depart en masse, but return again and again in this feed and flee dance. This scenario continues to repeat itself almost daily at our house. You can imagine by now how much money we have now "shelled out" on sunflower seed. However, it has been rewarding for us and fellow birding visitors who have added this special bird to their "Life" bird list.Local bird expert Larry Collins owns Wild Birds Unlimited, 2454 Hwy. 6&50, which caters to folks who want the best backyard birdfeeding experience possible. Email your birdfeeding and birding questions to firstname.lastname@example.org and he'll answer them in his bi-weekly Q&A column in the Free Press.