Wednesday's Wildlife: Calgary's Deer

The fall rut brings dramatic changes to deer behaviour, including sparring matches like this as bucks compete for mates. These seasonal shifts often make deer more visible—and more unpredictable—across Calgary.

Each fall, as daylight shortens and frosty mornings arrive, the rut returns. Across Calgary’s parks and neighbourhoods, deer behaviour shifts. Bucks grow restless and roam farther, their focus narrowed by the annual breeding season. This seasonal change, called the rut, is nature’s way of continuing the population, but it’s also the beginning of a story that unfolds throughout the year. At Calgary Wildlife, we use this moment to reflect on the broader life cycles and challenges faced by Calgary’s urban deer. Understanding the animals we share space with, how they behave, why they show up in our yards, and when not to intervene, helps keep wildlife wild and communities safe.

In Calgary, we share our urban landscape with two species of deer: mule deer and white-tailed deer. Both belong to the genus Odocoileus and share the typical traits of North American deer: four-chambered stomachs for digesting vegetation, a seasonal coat that thickens in winter and sheds in spring, and a life cycle closely tied to daylight and seasonal change. As prey animals, they rely on keen hearing, a wide field of vision, and acute sensitivity to movement. The males, known as bucks, grow new antlers every year, adding several centimetres of growth per day in summer (Price & Allen, 2004). These harden for the rut, then are shed in late winter before the cycle repeats in spring. Their breeding season occurs each fall, and females typically give birth once a year, usually to one or two fawns.

Mule deer (left) and white-tailed deer (right) are easy to tell apart by their tails. Mule deer have a small black-tipped tail, while white-tailed deer have a large tail with a brown upper surface and a bright white under surface, which they flash when alarmed.

Mule deer (Odocoileus hemionus) have large, “mule-like” ears and a short tail with a distinctive black tip. Their antlers fork and re-fork in a branching pattern. Mule deer often feed in open areas and are generally more tolerant of human presence than white-tails, which is why they tend to appear more conspicuously in some Calgary neighbourhoods (Miistakis Institute & City of Calgary, 2021). They rely heavily on shrubs, twigs, leaves, and seasonal vegetation, adjusting their diet throughout the year based on what’s available.

White-tailed deer (Odocoileus virginianus) are more secretive and prefer wooded areas, coulees, and the cover offered by river valleys. They are known for their broad tail, which flashes bright white when raised: a well-known alarm signal among deer. White-tailed antlers grow from a central beam with tines branching upward. Wildlife-camera data collected across Calgary shows that white-tailed deer are detected more frequently in the city’s natural areas, particularly in treed corridors or at times of day when human activity is low (Miistakis Institute & City of Calgary, 2021). This aligns with their preference for denser cover and their tendency to move more cautiously through human-modified environments.

Both species are native to Alberta, both participate in the fall rut, and both navigate the city according to their own ecological strengths. Their differences in behaviour, habitat preference, and visibility shape the way Calgarians encounter deer throughout the year.

Mule deer (left) and white-tailed deer (right) differ in their antlers. Mule deer antlers fork and re-fork in a branching pattern, while white-tailed deer grow antlers from a single main beam with tines projecting upward.

The rut is a highly active period, marked by dramatic behaviour changes, especially among male deer. Bucks may spar, mark territory with rubs and scrapes, and pursue does as they come into estrus, their fertile period. In Alberta, this typically peaks in November, though timing can vary slightly by species and region. Because deer are more mobile and distracted during this time, people may notice them in unusual places: crossing busy roads in daylight, showing up in cul-de-sacs, or even getting tangled in backyard furniture. The increased movement also raises the risk of collisions. Transport Canada data shows November is the month with the highest wildlife-vehicle collisions nationwide, with most incidents occurring at dawn or after dark (Transport Canada, 2020). It’s a vivid reminder that while deer may seem quiet or shy, their seasonal patterns bring them closer to us than we sometimes realize.

November is peak collision season for deer, especially at dawn and dusk when they’re most active, but during the rut they may move unpredictably throughout the day—making roadways particularly risky.

During the rut, it’s also important to give deer plenty of space. Bucks can become hyper-focused, territorial, and defensive when competing for does, and even normally calm animals may behave unpredictably if they feel challenged. Deer are large, powerful animals, and a buck’s antlers and hooves can seriously injure a person or pet if he feels threatened or is startled at close range. Alberta Parks recommends staying at least 30 metres (roughly 100 feet) away from deer and supervising pets, especially dogs, around wildlife (Alberta Parks, 2025). Steering well clear of rutting deer helps keep both people and wildlife safe, and ensures these animals can complete their natural seasonal behaviours without added stress

As winter settles in and the rut winds down, deer return to quieter patterns. Bucks shed their antlers later in the season, and does, many now pregnant, begin to seek winter shelter and browse. Calgary’s urban greenspaces offer ideal conditions: natural corridors, patchy woodland cover, and readily available food. Nose Hill Park, the Bow River Valley, and Fish Creek Provincial Park are known hotspots, but it’s not uncommon to see deer grazing along boulevards or resting near backyard hedges. Mule deer especially thrive in open terrain with shrubs and low human interference. Residential areas that border wild or semi-wild land tend to see the most deer traffic.

Fish Creek Provincial Park is one of Calgary’s key wildlife corridors, offering deer the shelter, food, and quiet pathways they rely on as they move through the city year-round.

So what draws deer into neighbourhoods? The short answer is food and shelter. Deer are opportunistic foragers and find many ornamental plants irresistible. They’re especially fond of tulips, hostas, cedar hedges, crabapples, and fruiting trees. Bird feeders, vegetable gardens, compost piles, and even lawns with certain fungi can also act as attractants. A yard with cover, such as evergreens, low fences, or dense corners, offers security for resting. Water sources, like ponds or birdbaths, may draw deer in dry months. Understanding what draws deer in can help residents make informed choices about how to prevent them from entering their yard, whether that means securing compost, choosing less palatable plants, or modifying spaces that offer easy cover. Being aware of these attractants helps reduce close encounters and allows deer to stay safely within natural green corridors rather than residential spaces.

Backyard bird feeders can unintentionally attract other animals looking for an easy snack, like deer, who quickly learn to check them for spilled seed.

Then comes spring, and with it, fawning season. In Calgary, most deer fawns are born in late May through June. A newborn fawn is an incredible example of natural adaptation. Its coat is covered in white spots, it emits little scent, and it instinctively stays motionless for long periods. This helps it avoid detection while its mother browses elsewhere. For people unfamiliar with this behaviour, it can look like abandonment. Each year, Calgary Wildlife receives calls about lone fawns curled in yards, ditches, or grassy parks. Almost always, these fawns are healthy, and their mothers are close by.

A fawn curled quietly in the grass is almost never abandoned. This still, camouflaged posture is its natural way of staying safe while its mother feeds nearby.

Fawns should never be moved unless they are visibly injured or there is clear evidence of prolonged separation from their mother and a rehabilitation centre has been contacted for guidance. A doe will return to nurse her fawn at intervals, most often at dawn and dusk, and the long periods of stillness in between are a natural survival strategy. Intervening too soon can cause unnecessary separation, create stress, and even lead to injury. One of the most serious risks for deer in a rehabilitation setting is capture myopathy, a potentially fatal condition triggered by stress. When an animal is chased, handled, or confined, its body can respond with a cascade of physiological changes, including muscle breakdown, heart complications, and kidney failure.

At Calgary Wildlife, we take extensive measures to reduce the risk of capture myopathy. We handle fawns and other vulnerable patients as little as possible, keep their enclosures quiet, and work to maintain a calm environment that minimizes stress. Some procedures, such as administering medication or treating wounds, cannot be avoided, which means there is always some level of risk for prey species in human care. This is why it is so important to be discerning about whether an animal truly requires intervention. For healthy fawns, staying with their mother is always the safest option, which is why we emphasize prevention first: don’t pick up wildlife unless it’s clearly necessary.

This fawn, admitted to Calgary Wildlife in 2022 following a dog attack, stayed in our care for 255 days before being successfully released in April of 2023.

Living alongside deer means recognizing that these animals navigate our city according to instinct, not intention. Throughout the year, their movements follow predictable rhythms: seeking food in winter, birthing fawns in spring, roaming widely during the fall rut. The best way we can help is by giving them the space and calm they need to move safely through those natural cycles. People can support deer year-round by slowing down on roads near parks and river valleys, keeping dogs leashed in wildlife-rich areas, and being mindful of how landscaping and yard features may attract or deter deer. Small actions such as storing attractants securely, driving cautiously at dawn and dusk, and observing quietly from a distance make a real difference in reducing stress and preventing unnecessary conflicts. And when a deer truly is in trouble, Calgary Wildlife is here to help. If you’re ever unsure whether intervention is needed, reaching out for advice before acting is one of the most meaningful ways to protect wildlife in our city.

Support a patient

For assistance with injured wildlife, please contact the Calgary Wildlife Rehabilitation Society at 403-214-1312.

Herds of deer are a common sight along Calgary’s open hillsides and river valleys, moving together through the seasons as they navigate the edges between city and wilderness.

References:

• Alberta Parks. (2025). Wildlife and you – Outdoor safety. Government of Alberta.https://www.albertaparks.ca/albertaparks-ca/advisories-public-safety/outdoor-safety/wildlife-and-you/

• Government of Alberta. (n.d.). Human–wildlife conflict: Deer.  https://www.alberta.ca/deer

• Miistakis Institute, & City of Calgary. (2021). Calgary Captured: Three-year technical report (2017–2020). https://www.rockies.ca/files/reports/Calgary%20Captured_3%20Year%20Technical%20Report_Final.pdf

• Price, J., & Allen, S. (2004). Exploring the mechanisms regulating regeneration of deer antlers. Philosophical Transactions of the Royal Society B: Biological Sciences, 359(1450), 809–822 .https://doi.org/10.1098/rstb.2004.1471

• Transport Canada. (2020). Wildlife–vehicle collisions: Traffic safety highlights. Government of Canada. https://tc.canada.ca/en/road-transportation/publications/statistical-review