My family always eats a big meal around Christmas, and this year, that got me thinking. What do deer eat this time of year? During the spring and late summer they feast on new growth – leaves, grasses, and herbaceous plants (like spring wildflowers). In the late summer and fall they shift to fruits, nuts, acorns, and farm crops.
My family always eats a big meal around Christmas, and this year, that got me thinking. What do deer eat this time of year? During the spring and late summer they feast on new growth – leaves, grasses, and herbaceous plants (like spring wildflowers). In the late summer and fall they shift to fruits, nuts, acorns, and farm crops.
But those foods aren’t around in winter. Deer don’t hibernate, and a typical adult deer needs 4 to 8 pounds of food every day. As the weather turns cold, they meet that need by munching on tree seedlings, twigs and buds.
This winter diet is part of why deer can have such a major impact in the woods. At best the nutritional quality of these foods is poor, so deer eat a lot of them. If you walk along worn game trails in the woods, you can easily spot deer browse if you know what to look for. Keep an eye out for “clipped and ripped” twigs. Deer have an overbite, so they can’t completely sever a twig the way a rabbit’s scissor-like front teeth can. Instead, a deer’s teeth cut through most of the twig, and then the deer rips the remainder off with its lips. This creates a tag-like bit of bark that is unique to deer browse.
You can see the “ripped” browse clearly on these close-ups of browsed twigs. The one in the middle is sawed off cleanly and was eaten by a rabbit. The ones on the left and right have jagged ends, which indicate deer browse.
Photo credit: Tim Pierson, Penn State Cooperative Extension
Deer tend to eat on the move, clipping a twig here, munching a seedling there. When they become more numerous, though, you can find areas of heavier browse. Repeated browsing of tree seedlings sculpts them from straight and tall to short, “hillbilly bonsai” that have a difficult time growing beyond where deer can reach.
A normal American beech seedling will grow straight up (left), but when repeatedly browsed by deer, it will contort into a “hillbilly bonsai” (right) that has difficulty growing taller.
Photo credits: Tim Pierson, Penn State Cooperative Extension
It doesn’t take that many deer on a woodlot to impact your undergrowth. Research suggests that a “healthy” deer herd – one that’s in balance with the food the woods can provide – is only around 15 deer per square mile. Populations that exceed 50 or 60 per square mile can result in starving deer.
You can get an idea of how big your local deer population is by examining which plants on your woodlot get browsed, and how heavily they’re browsed. The more clipped twigs and bonsai trees you find, the higher the population. In areas with more than 30 deer per square mile, you may be hard-pressed to find any seedlings at all, browsed or otherwise. They’ve all been eaten to the ground by hungry deer.
If you want to get a better sense of whether deer are impacting your woodland, this spring, consider trying the MyWoodlot Activity “Assess Deer Impact on My Land.”
