It is easy to understand the stress period that corresponds with winter. It is cold; in human terms, that automatically signals danger. However, to a deer temperature is not nearly as important as we may think. In most cases, they are equipped to handle it. When the temperature bottoms out and stays there, deer will react (after an initial feeding spree that may last a few days) with a reduction in their metabolism that more or less permits them to shut down for several days.
The real stress of winter occurs in areas with prolonged deep snow and/or limited food sources where access to feed is impossible. Then, the combination of cold and poor nutrition will create stress that will limit future antler development, fawn survival and the health of fawns that are yet to be born.
Having an ample supply of fall body fat to draw on is critical to health and maintenance in the depths of winter. And great winter food sources, especially those high in energy (carbohydrates) is important when the weather breaks and the deer get back on regular feeding patterns.
Intuitively we all understand winter stress; it makes sense to us in human terms. However, this article is about the summer needs of deer. Many deer managers fail to appreciate the significance of a second stress period.
Mid-summer is nearly as stressful as mid-winter. The reason again relates to food quality, or the lack thereof. In the summer, the deer have additional needs, which serve to increase the stress. Bucks are growing antlers and does are lactating to feed their fawns. Both activities take a huge toll on their physical resources. At this time of the year, their food (especially their native browse) is mature, comprised mostly of stems, often dried up like overcooked bacon.