NATURE’S VIEW
Is This What We Call Winter? In praise of deep snow and cold temperatures By Dave Anderson
P
erhaps you’ve just come inside from shoveling, snow blowing, or sledding? I hope so because until late January, most of New Hampshire still awaited a significant first snowfall. Remember? Daily high temperatures remained in the 30s and even 40s during December and January. Temperatures spiked into the 60s in November! Regression to average should finally deliver the heavy snow we expect. As the temperatures yo-yo, it leaves me thinking about our forests and wildlife and how they might respond to this weather that’s far from normal.
(OPPOSITE PAGE) COURTESY OF SOPHIE OEHLER; (THIS PAGE) RYAN SMITH
Weird Weather Erratic winter temperature fluctuations impact precipitation and snowpack. Meteorologists coined the term “winter weather whiplash” for the succession of low pressure accompanied by warming temperatures, wind, and rain with marginally frozen precipitation. Rain events are followed by high pressure, colder temperatures, and a hard re-freeze, which create an ice-encrusted snowpack. It’s a whiplash effect that leaves humans and wildlife reeling. Beyond impacts to winter recreation and economic tourism, changing weather patterns can affect trees and wildlife best adapted to cold temperatures and deep snow.
Wildlife Woes In response to shorter day length in autumn, hormonal changes cause snowshoe hares and short-tailed weasels to turn white in winter to better blend into a snowy forest floor. Without snow, these northern species are more visible and more vulnerable to predators. A deep snowpack provides thermal insulation and concealment for subnivian
A late January rain storm followed by a flash freeze caused a farm field to glaze over in Milford, N.H.
wildlife, including mice, voles, shrews, and red squirrels, which inhabit underthe-snow burrows linked by a maze of tunnels. Bobcats, coyotes, foxes, and owls hunt these animals. Extremely deep snow makes it difficult for some predators to hunt while a low snow year can impact rodent populations. Rain on frozen ground will flood rodent burrows drowning mice or driving them indoors. Freeze-thaw cycles form an impenetrable crust on top of the snow, and barred owls are impacted when this crust prevents them from reaching rodents beneath the top layer. Foxes and coyotes may experience similar difficulties. The 2022 seed crop was spare with few acorns, beechnuts, and a meager wild apple crop. Rodent populations were low following a mediocre mast crop in ‘21. The scarcity ripples across the oak forest food chain. As rodent populations bottom out,
predators—bobcats or Cooper’s hawks— turn their attention to backyard mourning doves, turkeys and gray squirrels. All things equal, lower predator birthrates should follow this year. As for 2023 wildlife “winners,” a lack of snow and prolonged cold improves survival for New Hampshire’s overall deer herd as individual deer conserve heat calories and are spared the exertion of wading in deep snow. Turkeys travel readily on bare winter ground and porcupines continue to graze frozen grass nightly in January. As for our resident predators— coyotes, foxes, and bobcats—they may find hunting easier and find available mates and dens more readily during their late February and early March breeding seasons. According to University of Massachusetts Wildlife Biologist Jeff Boettner, whitefooted mice population densities can Winter 2023 FOREST NOTES | 15