A white-tailed deer with “sleigh feet” wanders by a shed in Harpswell. The dangerous condition results from winter feeding of deer. (Shannon Hillman photo)
Imagine that your toenails have grown several inches long, curling upward and preventing you from wearing footwear of any kind. Winter confronts you with ice and snow, so walking is painful and dangerous. Suddenly you are forced to stumble away from a dangerous predator, putting you in mortal danger.
With apologies as necessary, I chose that graphic introduction to illustrate a grave risk for white-tailed deer when they are exposed to winter feeding by well-meaning humans. The condition is termed laminitis but is sometimes referred to as “sleigh hoof” or “foundering.” It is a terrible affliction for a deer, condemning them to death by predation or auto accident.
Thanks to Shannon Hillman for making me aware of a case in Harpswell last winter, the small doe shown in the photo. Scientists estimate that a normal deer’s hoof, made of keratin like our hair and nails, grows more than 2 inches annually but is continually worn down by walking. With laminitis, the hoof grows irregularly and leaves the deer in perilous condition.
People generally feed white-tailed deer out of compassion, just as we feed wild birds with suet and sunflower seeds. Scientific studies have shown that supplemental feeding of songbirds is a net positive for the species that remain in Maine over the winter, even though some birds succumb in periods of severe weather. But the same is not true for deer because of the nature of their digestive tracts.
Deer are members of the cervid family, along with moose and elk. Cervids are classed as ruminants, along with cows, sheep and goats. All of them have four stomach chambers, including a rumen.
The rumen holds a complex but balanced mix of gut microbes, including bacteria, fungi and protozoa. Those microbes are responsible for breaking down food and starting a fermentation process before food is regurgitated and chewed again. This partially digested food is known as the “cud.”
The microbial cocktail changes gradually over the year as deer find different food sources of varying nutritional quality. A summer diet of carbohydrate-rich grasses and forbs requires a different microbe population for proper digestion than does a winter diet of low-carbohydrate tree buds, bark, needles, or your prized rhododendron leaves.
The problem arises when wintering deer are presented with large quantities of carbohydrate-rich foods such as cracked corn, oats, hay or apples. In a period of cold weather and inadequate natural foods, deer will eat as much corn as possible. This can cause gastric distress, malnutrition or death for the animals.
The surge of carbohydrates triggers an explosion of stomach bacteria, including streptococcus, that produce large quantities of lactic acid in a condition called acidosis. The pH of the rumen falls, killing beneficial microbes and triggering serious inflammation. An inflamed rumen accumulates fluid, promoting dehydration of the deer that may lead to hypothermia. Equally serious, the rumen struggles to absorb nutrients, so the animal may starve despite a belly full of corn. Not only can acidosis kill in a matter of days, but surviving animals have permanent damage to their rumens or develop laminitis as mentioned above.
As described in past articles, the deer herd in much of Southern Maine already exceeds the carrying capacity of our habitat. Feeding deer in winter exacerbates this problem. While it is tempting to feel that feeding deer may help individuals survive, death is a natural part of their life cycle and there are many other creatures that survive on protein-rich winter kill. More significantly, boosting deer numbers in this manner creates an unbalanced ecosystem with devastating results for forests and all the creatures within them.
Author John Litvaitis wrote about two detailed plant inventories taken 66 years apart at a specific site in the Allegheny National Forest, in 1929 and 1995, a time of significant deer herd growth. He writes, “In the 1995 inventory, more than 80 percent of the species of herbs, wildflowers and shrubs present in the 1929 inventory had disappeared.” Over-browsing by deer can wipe out rare plants like trillium, limit insects required by nesting birds, and stunt the growth of oaks and maples. This favors invasive plants or trees such as birch and beech that are less valuable for timber and wildlife.
In summary, wildlife biologists and game wardens across the country advise that feeding deer in winter is not a kindness but misplaced compassion. Far better that we concentrate on habitat improvements to increase the carrying capacity of the land around us for all wildlife.
Ed Robinson’s latest book, “Nature Notes from Maine Vol. II: Puffins, Black Bears, Raccoons & More,” is available from the Harpswell Heritage Land Trust. All profits support HHLT’s conservation and education efforts.
