What Interferes With A Deer'S Survival?

Deer are majestic creatures that roam fields and forests, foraging for food. But many factors can interfere with a deer’s ability to survive. In this article, we’ll explore the main threats to deer survival so you can understand what makes life difficult for these animals.

If you’re short on time, here’s a quick answer to your question: Loss of habitat, lack of food, severe weather, predators, and hunting all interfere with a deer’s survival.

We’ll take a closer look at how each of these factors impact deer populations and reduce their chances of survival. We’ll also discuss how human activity and management strategies aim to support deer survival. Let’s dive in to learn what interferes with a deer’s ability to thrive.

Habitat Loss

Habitat loss poses one of the greatest threats to deer populations across North America. As urban development expands into former forest and grassland areas, deer lose vital shelter and food resources they need to survive.

Agricultural practices also eliminate natural habitat, while logging and mining disrupt remote wilderness areas that previously served as refuges from human activity.

Urban Development

Over the last few decades, urban sprawl has increasingly encroached on deer habitats. Suburban neighborhoods, shopping centers, and roads now cover areas that once contained vital wintering yards and breeding grounds.

From 1982 to 1997 alone, urban development claimed over 10 million acres of wildlife habitat in the United States. Without sufficient shelter and nourishment, deer populations decline. Those able to adapt to urban settings face increased dangers from vehicle collisions, predation by dogs, and conflicts with humans.

Agriculture

Modern agricultural practices have dramatically altered natural environments. Clearing of forests for croplands and pastures removes vital food sources and cover. Agricultural fields offer poor nutrition compared to the diverse native plants deer forage.

Fertilizers, herbicides, and insecticides taint the surrounding landscape. Fragmentation from fences, roads, and crop patterns impede migration routes. Monocultures of crops like corn also increase susceptibility to winter starvation by providing little fallback food when snow covers low-growing agriculture grasses.

Logging and Mining

Commercial logging and mineral extraction continue to degrade remote deer habitats. Large-scale timber cutting removes forest cover and destroys understory vegetation. Road systems break up habitat and enable greater human incursions.

Contamination from mining chemicals can poison water sources and plants. A study in Montana found that clear-cut logging reduced deer habitat suitability by up to 80%. Moreover, displaced deerconcentration in remaining habitat increases over-browsing and vulnerability to predation.

While logging practices have improved, timber production still substantially degrades wilderness sanctuaries.

Food Scarcity

Overpopulation

Deer populations have exploded in many areas due to lack of natural predators, bans on hunting, and ample food sources provided by agriculture and suburban landscapes. Too many deer for the available habitat leads to food scarcity, as the deer over-browse their food resources.

Research by wildlife agencies has shown deer densities of over 100 per square mile in some urban and suburban areas, compared to natural densities of only 10-20 deer per square mile in wild forested areas (1).

At high densities, deer can remove nearly all the vegetation they can reach, up to 6 feet high.

Forage Competition

Deer must compete with other wildlife and livestock for food sources. Areas with elk, cattle, or horses see increased competition for the same grass, shrub, and tree food resources that deer rely on. Competition is most severe during dry conditions when food is already scarce.

A Texas A&M study found that cattle reduced available forage for deer by 20-60% depending on the habitat type (2). Cattle are often able to access and overgraze food sources that deer depend on but can’t reach, like grass under oak trees. This leaves deer with lower quality food options.

Climate Change

Climate change can reduce deer food sources in several ways. Increased drought and high temperatures can dry up important food plants and reduce their nutritional quality. Earlier springs cause key food plants to bloom and mature earlier, making them unavailable to deer when they need them most in summer and fall.

Milder winters allow more insect pests and deer parasites to survive, further stressing deer. Extreme weather like flooding washes away food plants and makes food harder to access. A Penn State study predicts that climate change could reduce plant diversity up to 10-20% in Pennsylvania forests, limiting food options for deer (3).

Year	US Deer Population	Deer-Vehicle Collisions
2000	28 million	1.5 million
2010	33 million	1.9 million
2020	38 million	2.2 million

Severe Weather

Cold Temperatures

Deer can struggle to survive frigid winter temperatures. Prolonged exposure to cold can lead to hypothermia, frostbitten extremities, and even death. Deer rely on fat reserves and shelter to make it through harsh winters.

Deep snow can make it challenging for them to find food and can quickly deplete fat stores (QDMA).

During extremely cold snaps, deer herd together to conserve body heat. They may bed down in sheltered areas like evergreen thickets. Conservationists advise leaving brush piles, tall grass, and shelterbelts for deer to utilize (TPWD). Providing emergency food plots can also assist their survival.

Deep Snow

Deep snow exceeding 16 inches can prevent deer from accessing food sources (Realtree). As they tunnel through drifts, they quickly burn calories while exerting significant energy. Deep snow can also conceal obstacles and predators.

Consecutive days trudging through heavy accumulation adds physical strain. If unable to replenish energy reserves, deer perish. Harsh conditions coupled with depleted fat stores diminish chances of enduring prolonged snow cover (QDMA).

Conservationists clear trails in public lands to improve accessibility during substantial snowfall events.

Flooding

Spring flooding can destroy deer habitat and restrict access to food. Rising water inundates fields, forests, and bedding areas used by deer. Floodwaters often carry substantial debris that can injure deer.

A University of Georgia study discovered flooding increased deer mortality and reduced fawn production (UGA). Drowning, injuries, and waterborne diseases are all heightened dangers posed by flooding. Displaced deer also face elevated risks wandering in unfamiliar surroundings with additional obstacles and potential predators.

Predators

Wolves

As apex predators, gray wolves pose one of the biggest threats to a deer’s survival. Studies show that wolves account for up to 80% of natural deer mortality in areas where they coexist. With powerful jaws and sharp teeth, wolves can efficiently kill adult deer.

According to the Idaho Department of Fish and Game, a single wolf can consume up to 20 pounds of meat in one sitting, often targeting the most vulnerable deer in a herd.

In addition to direct predation, the presence of wolves also causes behavioral changes in deer that make their lives more difficult. Deer in wolf territory are more vigilant, spend more time in forested cover to hide, and reduce their use of open meadows where they could more easily be caught.

This extra stress and energy expenditure makes deer more susceptible to starvation and other health issues. Overall, the combination of direct predation and fear-based effects make wolves a significant challenge for a deer’s day-to-day survival.

Bears

Bears are another major predator of deer, especially newly born fawns. Black bears, brown bears, and grizzly bears have all been documented killing and eating deer. Bears emerge from hibernation in the spring, which coincides with deer giving birth to fawns.

This makes the young deer an easy source of food for hungry bears.

Studies show that bears can account for up to 21% of fawn mortality in certain areas. The predators use their strong sense of smell to track down hiding fawns. Once caught, fawns stand little chance against a bear’s sheer strength and powerful jaws.

Beyond fawns, adult deer can also fall prey to bears in run-ins. Deer typically rely on speed and agility to escape from predators, advantages that are minimized if a bear takes them by surprise at close range.

Bobcats

While not as dangerous as wolves and bears, bobcats do kill deer occasionally, typically targeting fawns or bedded adults. Bobcats are stealthy ambush predators that use quick bursts of speed and sharp claws to take down prey. An adult deer is usually much too large for a bobcat to kill.

However, fawns or weakened deer can fall victim. One study in Maine found that 18% of bobcat scat contained remnants of young deer.

Bobcats are opportunistic hunters and will target vulnerable deer when given the chance. Their keen sight, hearing, and smell help them locate hiding fawns during the spring. And if an adult deer is sick or disabled, a bobcat may test its luck in attacking.

While healthy adult deer can often ward off a bobcat attack, they remain a constant minor threat. Bobcats are estimated to only account for up to 7% of overall deer deaths per year. But in certain habitats, their role in limiting deer populations can be more significant.

Hunting

Hunting deer for food and sport can significantly impact deer populations if not properly managed. Three key ways hunting threatens deer survival are through overharvesting, poaching, and wounding loss.

Overharvesting

Setting appropriate hunting quotas and regulations is crucial to prevent overharvesting. When too many deer are killed, it can decimate local populations and interfere with the species’ ability to recover.

Management plans factor in breeding rates, habitat capacity, winter severity, and other data to set targets for the maximal sustainable yield.

For example, the state of Wisconsin allows hunters to take up to 350,000 deer annually across multiple seasons as part of a comprehensive deer management program (1). Despite these precautions, some areas have seen deer populations decline up to 15% in recent years due to liberalized “earn-a-buck” rules and back-to-back mild winters allowing higher survival and reproduction rates (2).

Wildlife officials now face pressure to restrict harvests to stop further decreases.

Poaching

Illegal poaching also endangers deer outside of regulated hunting. While the exact scope of U.S. deer poaching is unknown, estimates suggest >100,000 deer may be illegally killed each year (3). Unlike legal hunts designed to control populations, poached deer are often killed indiscriminately without regard to age, sex, or sustainability.

Tactics like jacklighting deer at night, killing them over piles of bait, or shooting from vehicles allow poachers to easily exceed limits. The Internet and global commerce also drive demand for illegal deer harvests to obtain trophy racks or produce products like ornamental antlers for foreign markets.

Wounding Loss

Another less considered but significant threat is wounding loss – deer injured or killed by hunters but not retrieved. Marked deer research over 13 studies shows wounding rates average 20% and up to 50% for archery hunts, leaving large numbers of deer to die from wounds or become easier targets for predators (4).

Managing all these hunting impacts on deer survival remains an ongoing challenge. Yet with responsible quotas, enforcement, hunter education, and season adjustments, science-based management provides solutions to preserve both recreational hunting opportunities and healthy deer herds for future generations.

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Conclusion

In summary, deer face a variety of threats to their survival, from human development encroaching on their habitat to predators looking for an easy meal. By understanding the challenges deer populations face, we can better advocate for conservation efforts that preserve their habitat and give them the best chance to thrive.

While deer are amazingly resilient animals, they still need protection from the many factors working against them. With care and management of wilderness areas, we can ensure deer continue inhabiting our fields and forests for generations to come.

What Interferes With A Deer’S Survival?