"Freedom from want and fear."

Our first thaw in 4 weeks, so here's a shot in honor of melting snow everywhere:

Rough-legged Hawk (Buteo lagopus),
Rollins Savanna FP, Lake Co, IL 1/29/2014

Along with a quote from one of my favorite authors, Aldo Leopold:

"The rough-leg has no opinion why grass grows, but he is well aware that snow melts in order that hawks may again catch mice. He came down out of the Arctic in the hope of thaws, for to him a thaw means freedom from want and fear." (1)

Leopold was a keen observer, which explains why come November hawkwatchers across the US start studying maps of snow cover in Canada. Even once they reach their wintering grounds, snow plays an important part in their ecology. Sonerud found that Rough-legs tend to winter in snow free areas where possible, (2) and Schnell found that when snow cover exceeds 1 inch, they tend to cluster along roads. (3)

Mice, of course, are easier to catch when there's no snow, since they can tunnel underneath it where they can't be seen. (The temperature is often warmer under an insulating blanket of snow as well.) On the other hand, wolves have a much easier time hunting deer in deep snow. (4) By the same token, while many of us in Chicago were luxuriating in the warmer weather, skiers and snowmobilers were facing the end of their season. Whether it's hawks, mice, or us, tomorrow's forecast is as much a mirror as it is a picture.

(1) Leopold, A. (1949). A Sand County Almanac and Sketches Here and There. New York: Oxford University Press.

(2) Sonerud, G. A. (1986). Effect of snow cover on seasonal changes in diet, habitat, and regional distribution of raptors that prey on small mammals in boreal zones of Fennoscandia. Ecography, 9(1), 33-47.

(3) Schnell, G. D. (1968). Differential habitat utilization by wintering Rough-legged and Red-tailed Hawks. Condor, 70(4), 373-377.

(4) Huggard, D. J. (1993). Effect of snow depth on predation and scavenging by gray wolves. The Journal of wildlife management, 382-388.