For many wild game species, forage availability will vary drastically according to the time of year. Deer and elk diets are closely matched to what is the most abundant and most palatable in any one season. So anyone who is managing for these species and many others should pay close attention to the seasonal food sources in their area. This will help determine any limiting factors in seasonal forage availability and help to determine a management strategy for their property.
In my area during the early to late winter time period the staple forage type is woody browse. These are the dormant twigs and buds that grew on woody shrubs and young trees the previous growing season. At this time of year this is one of the few available food sources and during periods of deep snow cover it is possibly the only source. At times during the winter the snow may melt in some areas such as on south facing slopes, exposed ridges and lower elevation areas. In these areas there could be green cool-season grasses available, although it is rarely abundant. Cool season grasses are very hardy and will sometimes grow very slowly during the winter or stay green from growth in the fall providing a source of green forage for deer and elk. Also if there is snow on the ground, but it isn't too deep and it is light and fluffy then wildlife may be able to dig through it to reach the green grass underneath. One more possible food source during the winter months are winter persistent fruits. In my area wild roses will hold onto their rose-hips all winter long and can provide a very good supplemental food source during a time of year when forage quality is rather low. This is generally the hardest time of year for wild game so making sure you have a large variety of woody browse, open areas with grass and possibly some winter persisting fruits will really help game populations maintain themselves.
After the winter snows start to melt the next important time period is early through mid spring. During this time the most utilized food source will be the fresh growth of cool season grasses. This is when grass will be most utilized in my area, because it's new growth will contain a relatively high density of nutrients compared to other times of year. It is also the dominant forage type because most other plants have yet to start growing during this time. In some areas you will start to see some cool season forbs starting to increase in prevalence, but during this time growth is very slow so they will usually only make up a small part of the diet of deer and elk. Also during this time woody browse will still be available and utilized to a lesser extent, but it is still important in case a large early spring snowstorm buries lower growing forage.
The next time period of forage availability is mid spring through early summer. During this time cool season grasses will start to grow more course, less digestible and contain fewer nutrients, especially for deer, so use will decline. Elk, however, will likely still utilize grass as a moderate percentage of their diet because they are better adapted to digest more mature grass than deer. The main staple for this time of year, however, will switch to cool season forbs. Cool season weeds like prickly lettuce, clover, and salsify will be the most nutritious forage type available at this time and will be heavily utilized. In most areas this will be the most important time of year for deer and elk because at this time forage is at it's highest nutrient density and it's highest abundance. This includes the new green leaves and stems of woody plants, however in general forbs will still contain higher nutrient concentrations than browse during this time of year. At the end of this time period around early summer some species of soft mast such as cherries and some warm season forbs will become available, but they will make up a relatively small percentage of deer and elk diets until mid summer.
Once the summer heat and drought hits most cool season forbs will go to seed and die out or go dormant. During the time from early summer to the first frosts in early fall the green leaves and stems from browse will become the dominant food source. The green growth on most shrubs and trees will usually maintain fairly high nutrient densities throughout the summer especially compared to cool season forbs, which usually dry out by this time. This is mainly because woody plants generally have deeper root systems than forbs and can reach deep soil moisture late into the summer that allows them to continue to photosynthesize until temperatures dip below freezing in the fall. Also during this time warm season forbs will likely be available, but rarely are they abundant in our area. Some warm season weeds such as ragweed, lamb's quarters and amaranth make excellent and highly nutritious forage, but they are rarely abundant due to our dry summers, however if they are available they will likely provide the most nutritious forage around during this time. Also, this time of year is the best time for soft mast species. In our area we have cherries, plums, grapes, blackberries, raspberries, apples, pears and many other wild and feral fruits that provides a great high energy supplemental food source to deer and elk during the summer months. While deer and elk generally won't subsist off of this fruit it can make a relatively high proportion of their diets until about the middle of fall.
After the first couple of hard freezes in the fall most vegetation will turn brown and go dormant. However, their is a short period of time in mid fall after the first fall rains begin and before the really cold temperatures set in when cool season grasses and forbs have a short period of growth. During this time there might be just enough growth to provide a decent amount of forage for deer and elk, but it will still be a relatively small percentage of their diet. Once the leaves fall off the shrubs and trees deer and elk will again start to browse on the dormant buds and stems and this will usually make up the majority of their diet through the winter. Most of the summer fruit will be gone by this time as well, but some like apples and pears can persist for awhile until winter really takes hold and can provide a valuable supplemental food source for the last few weeks of fall. While not common in my area, hard mast, if available, can make another excellent high energy supplemental food source during the fall. In my area, although rare, some hard mast species include hazelnuts, walnuts and acorns from oak trees. Because of their rarity in my region I have decided to plant a large amount of hard mast producing trees and shrubs on my property and I'm hoping they will mature and produce abundant crops someday in the future.
Monitoring the different forage types as the seasons change can be an important part of developing a management plan for your property. Making sure wild game have abundant forage year round can really help populations expand, while neglecting forage in any one season can create a bottleneck in food sources and lead to lower numbers of game. As you can see, in my area browse from trees and shrubs make up the majority of the forage during most of the year. It would only make sense then for me to try and manage most of my property for an abundance of this forage type. So if your goal is to create excellent wild game habitat, research and monitor what the game are eating on your property on a seasonal basis. Then once you have a good understanding of these patterns you can figure out your limiting factors and plan accordingly and hopefully it will lead to abundant game populations in your future.
