“Watching deer forage for whatever bits of food they can find through the cold months of winter, I can understand why some people feel an urge to feed them. Only supplemental feeding isn’t helpful at all to deer. Instead, it’s detrimental to their digestive health, and it pulls them away from safer, more nutritious food sources.
“Supplemental feeding has little or no benefit to the overall health of deer,” said Nick Fortin, Deer Project Leader for the Vermont Fish and Wildlife Department. “Interestingly, northern deer will lose weight in winter no matter what or how much they are fed, even in captivity.”
Like virtually all animals living in climates where winter is cold and snowy, deer use a variety of adaptations to adjust and survive. In the northern part of the Northeast, they often gather in deer yards, where softwood cover offers shelter from wind and cold as well as decreased snow depth. As deer move to and through their winter shelter, they pack down paths, allowing for easier travel to food and quicker escapes from predators.
In winter, deer reduce their energy expenditures by hunkering down during extended cold stretches; this way they can focus their activity during times when temperatures are warmer. Similar to animals that hibernate, deer store fat – it can constitute up to 20 percent of their body weight, said Fortin – and they can use that fat as a sort of energy savings account.
A deer’s digestive system also goes through changes to cope with less abundant – and different – food sources. Deer are ruminants, which means they have a four-chambered stomach, like cows and sheep. Each chamber contains microorganisms to help with digestion. These microbes become tuned in to a winter diet of twigs and buds, nuts, any fruits and berries that persist, and whatever grasses they can find. A sudden change in diet – say to supplemental corn or rich hay – can wreak havoc on this system.”