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On our two acres just outside of Apollo (Armstrong County, PA) we have a group of deer that Deborah and I enjoy watching very much. Now these deer do a number of things that are annoying (they eat anything we try to grow in our garden, they mow down most of the volunteer and also any carefully planted tree seedlings, and they gobble down any black oil sunflower seeds that are left overnight in our bird feeders). But, they have also given us a great deal of pleasure over the years: I remember the newly born fawn one early June morning that walked up to our front porch on its still wobbly legs, I remember the twin fawns eating sour apples from the ground in our orchard in August, and many people remember the dioramas in our front yard in December of a group of deer (eating sunflower seeds, of course!) colorfully lit by our outside Christmas lights, causing a mini-traffic jam on our quiet street as people stopped their cars to look at the “reindeer.”
We shamelessly anthropomorphize our deer but recognize that they are wild animals interfacing with and trying to survive in a human dominated and in many cases human generated ecosystem.
I spend as much time as I can at my writing desk in the back room of our house. My desk faces a large window that looks out on our very sheltered back yard, and I have included in this blog many of the observations I have made from my “sit spot” by this window. The deer regularly pass through the back yard and have on occasion even come up to the window to get a closer look either at me working at my desk or at one of my cats who had taken over either the desk or the inside window ledge. As long as we don’t make any sudden moves, the deer are very content to stand and stare for many minutes on end.
Photo by ForestWander, Wikimedia Commons
One very interesting deer behavior that I have observed concerns the relatively large (7 to 8 individuals) winter group that crisscrosses through the yard and field throughout the winter. The group is made up of three older does and their now well grown fawns. In the afternoon or early evening the largest doe (who I assume to be the eldress of the group) leads the other deer in single file around the yard and field sampling a great variety of plants. The lead doe browses on the vegetation (the low hanging apple tree branches, the bushy crabapple tree twigs, the arbor vitae, the oak saplings, the hemlocks, the honeysuckle bushes, and so on) and one by one the members of the group walk up to the same spot after she has moved on, feed for a few minutes, and then move on to the next vacated feeding station. The orderliness of the process is amazing. It has occurred to me that the lead doe possesses the “group knowledge” of what browse is best to take or possibly what order of browse is most digestible. She may also have some knowledge about what intensity of browsing is suitable for the long-term, sustainable productivity of the habitat (but, probably, that is hoping for too much!). Possibly these feeding behaviors have been habituated in the lead doe by example and repetition in her youth, and, hopefully, they are being drilled into the younger deer. The winter diet of this group (significantly augmented by the sunflower seeds from my birdfeeders, of course) has maintained a good number of generations of these animals very well over the twenty-eight winters that I have observed them!
At the upper edge of our field we have a small orchard with apple, pear, and cherry trees. The trees are old and not well tended, so the fruit is usually small and frequently riddled with insects (the pears, though, from the Bartlett pear tree are some of the sweetest I have ever eaten!). I let the birds (especially the cardinals and the waxwings) have the cherries, and I leave the apples and most of the pears for the deer. Deborah made a great video of those fawns I mentioned earlier eating the green (and very sour!) apples. Their facial contortions and foot stompings as they bit into the sour fruit were remarkably human!
Photo from Pixabay
Since these deer are used to apples (they regularly dig frozen fruit out of the leaf litter under the snow), I feel comfortable putting out some apples through the winter for them. Many fruit stands and orchards advertise “deer apples” just for this purpose. You have to be careful, though, not to put out apples (or any other high calorie or exotic food) for the deer in the winter if those foods are not something that the animals have been regularly eating. A deer’s digestive system gets patterned to digest browse and those other “consistent” foods they find in its environment. A sudden exposure to corn, or apples, or rich hay could upset their digestive systems and possibly even lead to fatal consequences! Deer are very sensitive to changes in their diet!
Mostly, deer rely on their fat deposits for their metabolic energy in the winter. At the start of the winter a deer in prime condition may have as much as 30% of its body weight in fat! The fat is subcutaneous (which also adds to body insulation) and is also found extensively around the internal organs of their bodies. This is their “fuel tank” carefully filled through the spring, summer, and fall. In normal years these fat deposits represent enough calories to carry the individuals through to the next, bountiful spring.
Preferred winter browse for deer include cedar (like arbor vitae!), sassafras, apple, most types of maples, basswood, and flowering dogwood. Secondary browse includes hemlock, honey suckle, mountain ash, willow, white oak, and many other deciduous trees. Last resort choices for browse (sometimes referred to as “starvation food” because if you see these trees being browsed by deer you know that the herd is in trouble!) include pines, mountain laurel, beech, aspens, poplars, black locust and birches. (This browse data is from the New York State Department of Environmental Conservation).
You can tell if a tree or shrub has been browsed by deer because of the way deer feed. They use their lower jaw incisor teeth to crush a stem or branch against their upper jaw’s hard pad of cartilage. This feeding method results in torn (shredded) stems and branches rather than cleanly nipped off edges.
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The cellulose-rich food material is then passed through the deer’s four-part stomach and digested (at least somewhat) by the bacteria and protozoa that reside there. The low calorie nature of even these preferred winter browse species almost makes you think that the browse food is designed to make the deer feel like they have food in their stomachs even though they must be primarily living on their stored fat.
The deer are well insulated (and well camouflaged) by their winter coats. The gray-brown outer hairs cover a dense, wool-like undercoat and are very protective against cold, wet, wind, and snow. The hair shafts are also connected to tiny muscles in the skin that can lift and rearrange the angles and packing of the hairs to alter the degrees of insulation.
Deer behaviors also contribute to their winter survival. Small family groups typically form larger herds, and these larger herds confine themselves to the most sheltered and protected sub-sections of their broader, summer ranges. Our winter group is probably two or three family units, and their selected protected spaces are the woodlots, fields, and yards right around our Rose Street house!