White-Tailed Deer Ecology – Illinois Learn to Hunt

Line of five deer standing on green grass before a line of trees.

White-Tailed Deer Ecology

The white-tailed deer (Odocoileus virginianus) is the only deer species available to hunt in Illinois. Taking the time to learn more about ideal deer habitat, different types of deer sign and what they mean, and the cycle of deer behavior will make you a better hunter because you will know where to look for deer, what to look for to identify whether or not deer are actually present in the area, and how to use their behavior to your advantage. Understanding deer ecology will help you have a better chance at putting yourself in the right spot at the right time to take your shot.

Silhouette of hunter holding crossbow at sunset, the sky streaked with yellow, orange, and purple.

Deer Scouting Tips

Get a quick overview of key habitat features to look for when scouting deer, along with the different types of deer sign and what they indicate.

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Habitat Use

Habitats are areas where resources and environmental conditions are sufficient to allow for the survival and reproduction of a species. Deer are often considered generalists and can be found in a wide variety of habitats as long as a few key conditions are met. The term generalist simply refers to species that can thrive in many habitat types and feed on a wide variety of food sources. However, just because a species is a generalist does not mean it lacks preferred habitat types. For example, although deer require woodlands to survive, they are also often found foraging outside the woods in farmlands, stream/river corridors, and even grasslands.

The age of a forest often determines how many deer it can support. Early successional forests (young forests) provide ample diversity of food sources and vegetative structure that deer utilize as protection from predators and the weather. Often, areas considered young forests (early successional stage) are dominated by young deciduous (annually shed leaves) trees and shrubs, and contain forest openings dominated by grasses and other herbaceous vegetation. These areas provide ample feeding opportunities throughout the various seasons.

Vegetation that provides protection to an animal is commonly called “cover.” Dense thickets of young vegetation provide suitable cover for white-tailed deer.

Deer hiding in leafy brush, which is accented with red berries.

Feeding & Habitat

Deer are classified as browsers. This refers to a feeding behavior where they selectively consume a variety of vegetation. This includes leaves, twigs, buds, and shoots of woody plants, shrubs, and trees. Unlike grazing animals that feed primarily on grasses, deer are browsers and rely on a diverse diet to meet their nutritional needs, particularly during winter when other food sources are scarce. This behavior helps them survive the harsh Illinois winters by allowing them to take advantage of the available woody vegetation.

In Illinois, deer exhibit diverse feeding behaviors influenced by seasonal changes and habitat availability. During spring and summer, deer primarily consume a diet rich in forbs, leafy greens, and tender shoots. Agricultural fields also provide a significant food source, with deer often feeding on corn, soybeans, and alfalfa. This diet helps them build energy reserves and supports antler growth in males.

As autumn approaches, the feeding behavior of deer shifts to maximize fat storage for the winter. Acorns, nuts, and fruits become crucial components of their diet, along with agricultural byproducts such as corn and soybean leftovers. These high-energy foods are essential for sustaining deer through the harsher conditions of winter.

In winter, when food becomes scarce, deer adapt by browsing on whatever vegetation is available, including twigs, bark, and evergreen plants. They exhibit a high degree of selectivity, often seeking out nutrient-rich food sources to maintain their energy levels.

Female deer in a grassy field with short to medium-length, brown, dry grass.

While many hunters are aware of a deer’s propensity to gravitate towards white oak acorns during the fall, a year with poor white oak acorn production may prove challenging for some hunters to locate deer. Oak trees are classified in the genus Quercus and can be further divided into two distinct subgenera: Erythrobalanus (red oak group) and Leucobalanus (white oak group). While this classification may seem academic, there are distinct morphological differences between the groups that impact acorn production and ultimately dictate which acorn wildlife prefer.

Two green leaves — one with pointed lobes and the other with rounded lobes. — One way to remember the difference is to think of *red* oak leaves (left) as having *ragged* edges, and *white* oak leaves (right) as being *wavy*.

White oak acorns are the deer’s preferred acorns for palatability. However, in instances when white oak acorn production is low, red oak acorns can fill the void. Red oak acorns have a higher tannic acid content than white oak acorns, which gives them a bitter taste but often keeps them viable and edible after white oak acorns have been consumed. Importantly, white oak acorns mature in 6 months compared to an 18-month acorn maturation in red oaks. It is important to note that while red oaks take 18 months to mature an acorn, they are still producing acorns every year. The longer maturation period ultimately means they are less susceptible to weather events that may impact acorn production (e.g., drought).

Although there are roughly 20 oak species commonly found in Illinois, hunters do not need to identify every species. A basic skill set for identifying red and white oaks is important. Red oaks are characterized by having leaves that come to a point. These pointed leaves have bristles at the tips of the lobes and the leaf apex (see photo). White oak trees have leaves that do not have bristles at the tips of the lobes or leaf apex and are more rounded than pointed. Using the presence or lack of bristle-tipped lobes is the simplest way to identify the two groups; however, you may find yourself in an instance where the leaves are not easily identifiable, particularly after leaves fall.

Deer Sign

Game Trails

When looking for deer habitat, look for travel corridors (game trails). These corridors are natural funnels formed by existing vegetation or topography. Deer follow these funnels, as they provide a safe route from bedding grounds to feeding grounds.

Game trails/funnels are generally easy to spot, and they’re a great place to start scouting for other deer sign.

Grassy area under trees with a small trail of bare ground threading through it.

Scapes

Deer scrapes are a vital communication tool used by deer, primarily bucks, to convey important information to other deer in the area. These scrapes are typically small patches of ground where bucks have cleared away leaves and debris using their hooves, exposing the bare soil. Above these scrapes, bucks often rub their antlers or forehead glands against overhanging branches (termed licking branches), depositing scent from specialized glands located on their heads. This combination of visual and olfactory signals serves multiple purposes, including marking territory, attracting does, and establishing dominance hierarchies among bucks. The scents left behind in scrapes contain pheromones and other chemical markers that provide detailed information about the individual deer, such as its age, health, and reproductive status.

When a buck makes a scrape, he will put his two back legs together and urinate down his legs, causing the urine to pass over scent glands located on the inside of his legs near the knee joint.

During the rutting season, scrapes become especially significant as they play a crucial role in the breeding behavior of deer. Bucks will frequently revisit their scrapes to refresh the scent and ensure their presence is continually advertised. This repeated activity can help to establish a buck’s dominance over a particular area, as the scent markers signal to other bucks that the territory is occupied and defended. Conversely, does visit these scrapes to assess the suitability of potential mates. The information contained in the scent allows does to determine the genetic fitness and vigor of the buck, aiding in their selection process for breeding.

Scrapes also facilitate indirect communication between deer that may not encounter each other directly. The scents and markings left behind in scrapes can be detected and interpreted by other deer passing through the area, allowing them to adjust their behavior accordingly. For example, a subordinate buck may choose to avoid an area heavily marked by a dominant buck to prevent conflict.

Similarly, does can use this information to locate and congregate around the territories of the most fit and dominant bucks during the breeding season. This complex system of communication through scrapes plays a critical role in the social structure and reproductive strategies of deer populations.

Wooded area with a depression without leaf cover. — An example of a deer scrape

A series of tracks made in mud, with scattered leaves surrounding them.

Young buck standing in open area with an arrow pointing to the central part of the back legs and the text "Scent Gland."

Rubs

Deer rubs, created when bucks rub their antlers against trees, serve as an essential communication tool within the deer herd. These rubs are particularly prominent during the fall and early winter. The act of rubbing leaves visible marks on the tree bark and deposits scent from glands located on the forehead and around the base of the antlers. This scent contains pheromones and other chemical markers that convey critical information about the buck that produced it. This dual visual and olfactory mark helps establish a buck’s presence and territorial boundaries within its home range.

Rubs play a pivotal role in the social structure and breeding dynamics of deer. As bucks create these rubs, they are not only marking their territory but also signaling their readiness to mate. Other bucks in the area interpret these signals and can gauge the competition they face. A series of fresh, prominent rubs indicates a dominant and active buck, often deterring younger or weaker bucks from encroaching on that territory.

Slim-trunked tree with partially rubbed off bark among a leaf and grass-covered landscape. — Two examples of white-tailed deer rubs.

Tree with rubbed off bark amidst snow-covered ground. — Two examples of white-tailed deer rubs.

Scat

Deer scat, commonly called “deer droppings” or “pellets,” is an important piece of sign that every hunter looks for. Importantly, the shape and form of deer scat can vary significantly based on the type of food they consume. Typically, when deer feed on a diet high in fibrous plant material such as leaves, twigs, and bark, their droppings are small, round, and pellet-like. These pellets are often dark in color and relatively dry, reflecting the high cellulose content of their diet. This pellet form is common in the fall and winter months, when deer primarily consume woody browse because softer vegetation is scarce.

In contrast, when deer have access to lush, green vegetation such as grasses, forbs, and agricultural crops during spring and summer, their scat tends to be softer and more clumped. This change in diet, rich in moisture and nutrients, results in droppings that are less formed and can appear more like clumps or even loose piles. The color of the scat during this period is often lighter and greener, indicating the consumption of fresh plant material.

Small pellets of poop on grass. — Example of droppings from a fibrous diet.

Ball of scat made up of smaller balls squished together on dirt covered with scattered leaves. — Example of droppings from a fibrous diet.

Tracks

Deer tracks are a vital clue for hunters, providing insights into the age and gender of the deer in the area. A deer’s hoof print, or track, is composed of two main parts: the two-pointed toe impressions and, occasionally, impressions from the dewclaws located higher on the leg. The size, shape, and depth of these tracks can vary significantly based on the deer’s age and gender.

Roughly palm-sized hoof print in mud with an adult-sized glove next to it for scale.

Generally, larger and deeper tracks with broader toe spacing indicate a mature buck, as bucks tend to have bigger and heavier bodies compared to does. The track of a mature buck can measure around 3 to 4 inches in length, with a more pronounced and wider spread between the toes due to their larger hoof size and weight.

In contrast, the tracks of does and younger deer are usually smaller and narrower. Doe tracks tend to be more pointed at the front and closer together, reflecting their lighter body weight and smaller hooves. A doe’s track typically measures around 2 to 3 inches in length. Additionally, it usually leaves more delicate, less deeply imprinted tracks than bucks.

Fawns, or young deer, have even smaller tracks, often less than 2 inches long, and their hoof prints appear daintier and less defined, reflecting their lighter and less developed bodies.

Recognizing these differences in track size and shape can help hunters determine not only the presence of deer but also the likely age and gender of the animals frequenting the area.

Remember that the speed at which a deer is moving and the characteristics of the soil substrate (dampness, softness, etc.) can both make tracks appear to be produced by a larger animal than they actually were. For example, a fast-moving young deer can leave tracks with widely spread hooves that suggest an older, larger animal than it actually is. Similarly, deer can slide when walking in mud, which makes their tracks appear larger than they would in drier soil.

Pay special attention to the directionality of the tracks, as it can give additional insight into how a deer is moving through a specific area.

Beds

Deer beds are typically found in areas that offer good cover and a clear view of the surroundings, such as tall grass, thick brush, or forested areas with dense undergrowth. A deer bed looks like a shallow, oval-shaped depression in the ground, often lined with flattened vegetation or leaves. The size of the bed can vary, but it generally measures about 3 to 4 feet in length and 2 to 3 feet in width, large enough to accommodate a resting deer.

Grassy area with an oval shaped spot in the middle showing almost bare ground. — An example of a deer bed

Deer use beds to rest and ruminate between feeding sessions. They typically bed down multiple times throughout the day and night, using different beds within their home range based on factors such as weather, predation risk, and food availability. Bedding areas are carefully chosen to maximize safety and comfort; for instance, deer often select sites that offer a combination of concealment and a strategic vantage point to detect approaching predators. In cold weather, deer may bed in areas that receive ample sunlight to stay warm, while in hotter climates they seek shady, cool spots.

Bucks are generally solitary in their bedding habits and, as such, often select bedding locations that are slightly elevated or in open woods where they can keep an eye on potential predators. During the warmer months, they may bed down in areas that provide good visibility and access to food. Bucks, especially mature ones, tend to bed in different spots each day, constantly shifting to avoid leaving a trail of scent that could attract predators. During the rut, bucks become even more unpredictable, bedding in close proximity to does or in cover near high-traffic deer areas.

Does, on the other hand, are more social in their bedding habits and will often bed in groups for added safety. These groups, which can include young deer and other adult does, bed in areas with dense cover, such as thick brush or tall grass, which offers protection from predators. The close proximity of the two allows for better detection of danger. Bedding in family groups like this increases the number of eyes, noses, and ears on alert for potential dangers. Does also bed more frequently during the day, especially when tending to fawns. They tend to be less transient in their bedding choices compared to bucks, staying in familiar areas unless disturbed by threats.

By understanding the characteristics and locations of deer beds, hunters can better predict deer movements and plan their strategies to intercept them effectively.

During rut, bucks are likely to move closer to doe bedding areas and hang out downwind of those spots to better smell when does begin to enter estrus (which is triggered by changes in the amount of daylight [the photoperiod]). Marking locations where you find doe bedding areas on a physical or digital map is a good way to begin determining which areas might be good hunting spots, and help you plan your approach accordingly.

Deer Behavior: The Rut

The breeding season of white-tailed deer begins as early as October and is termed the “Rut.” Breeding activity peaks in mid-November, and most adult females are bred by the end of December. Some female fawns are capable of reproducing at 7 or 8 months of age. An individual female’s age and health will influence her reproductive capacity. Adult females usually produce twins, while females in poor condition or younger fawns often produce a single offspring.

Male deer with antlers sniffs the hind quarters of a female deer while standing in an area with green grass.

Rut is a popular time for many white-tailed hunters and for good reason. The normal, cautious behavior of deer is reduced in favor of breeding. Paying special attention to the different phases and associated behaviors of rut through field observations can help ensure you are in the best areas to succeed. During rut, anything can and will happen. That is what makes it fun!

Contrary to popular belief, rut is triggered by photoperiod, not temperature changes. The amount of daylight available in a given day triggers testosterone levels to increase in white-tailed deer males (bucks). Much of the natural world, from plant life cycles to hormone levels in wildlife, revolves around photoperiods. This results in a deer rut that is similarly timed each year and offers hunters an opportunity to experience one of the greatest few-week periods in midwestern forests. Several distinct rut phases occur throughout this period, and each phase allows hunters to strategically utilize a buck’s desire to breed in their hunt-planning processes. While weather, human activity, and other factors can influence deer movement patterns, the annual patterns remain remarkably stable.

Hard Antler Transition Phase (August – September)

The shedding of velvet (vascularized tissue) and transition to hard antler marks the earliest stages of a prolonged pre-rut. As the velvet is shed, bucks will begin making boundary scrapes and rubs throughout their home range. This behavior will continue throughout October. As the weeks progress, scrapes and rubs become focal points of communication. See the Deer Sign section for more information on rubs and scrapes.

Male deer with velvety antlers among yellow-flowered plants and tall grass.

Seeking Phase (Mid- to Late October)

Bucks will begin actively surveying and inventorying does and searching for that first doe to enter estrus (hot doe) in mid/late October, although that usually does not occur yet. Bucks and does will regularly use scrapes during this period. By urinating on the scrape, deer signal breeding readiness through urine and glandular secretions that contain pheromones.

Soft calling (e.g., grunt, light rattling) can be an excellent strategy to lure in younger bucks (sometimes mature bucks) during this phase, as their curiosity, along with increasing hormones, can cause them to investigate any calling.

Focus efforts on the downwind side of a doe bedding area, feeding area, or transition between the two. Bucks will routinely skirt the downwind side of these areas to scent check all the does for breeding readiness without alerting the does to his presence.

Male deer with a large rack of antlers looks over tall grasses.

Chasing Phase (Late October to Early November)

The next few weeks are a magical time to be in the woods for any whitetail hunter. Activity overall and daylight activity increase because most does are entering estrus, and bucks know it. During this chasing phase, expect more activity at scrapes and less overall feeding activity, particularly among bucks. Scrapes are often made along areas where a buck expects high concentrations of does to come across the scrape.

Focusing efforts adjacent to a scrape is usually a good strategy; however, be cognizant that most scrape activity occurs under the cover of darkness. Focusing on areas of high doe concentrations can also be an effective strategy. As bucks’ testosterone levels peak, calling can be extremely effective during this period. This phase is primarily comprised of bucks chasing does, hence “the chasing phase.” If a doe approaches that is cautiously overlooking her shoulder, ears on high alert, or just appears on edge, a buck could very well be behind her. Not always will the buck be right on her tail. Sometimes, he may lag 15 to 30 minutes; sometimes, he’s 20 feet behind her. During this period, I assume every doe has a follower and makes decisions with that in mind.

Calling can be extremely effective when conducted at the right time and under certain circumstances. One thing that you should be aware of is the doe-to-buck ratio for the area you are hunting. If there are ample does for bucks to choose from for breeding activities, calling success will be lower. Without the need for competition for mates between bucks, you may not see much activity in response to calling efforts. The opposite will be true in areas with higher buck-to-doe ratios.

Male deer with antlers running through a field of short, green grass with trees in the distance.

The Estrus (Peak Rut) Lockdown (Approximately November 10–20)

This time period is often the most challenging phase to hunt. The vast majority of does have entered estrus and are now receptive to buck breeding behavior. If you find a confluence of three or four major travel routes, you’re likely to see does. If you see does, chances are you’ll see bucks. This phase is characterized by a lockdown-style breeding period. During this phase, a buck will be in a secluded area alongside the doe for upwards of 24 to 36 hours and will breed several times. This may result in a multi-day period during which deer activity appears low and is restricted to dense, heavy cover. Afterwards, the buck will begin searching for other does to breed.

Male deer with antlers and female deer in a field of short, dry grass.

Second Rut (Early to Mid-December)

Unbred does will re-enter estrus 28 days after their first estrus. Additionally, some doe fawns may enter estrus during this period, depending on their health and body condition. Activity is not as heightened as the first rut, but some rutting activity can still be observed.

Female deer amidst tall grass covered in snow.