A question that comes up often among hunters is “How long does a deer live?”. This question honestly is more loaded than it seems, and the answers vary depending on many factors. One thing is for sure, the overall population and popularity of deer in North America has grown over the decades. This makes deer the most sought after renewable game resource in America.
On average, the life expectancy of a whitetail deer is between 2.9 years to 6.5 years.
The life expectancy of a mule deer is 9-11 years.
Deer with healthy populations, a lot of feed, and generally safe places to spend their winters live a lot longer than deer facing issues in any of those areas. A good example of this difference can be found in more sparsely populated regions out west compared to the more densely populated areas found in the east.
In states like North Carolina, where deer populations are wildly out of control while living on a limited range, we see mature deer between 3-6 years of age. A 6 year or older buck in North Carolina is by most accounts a deer near the end of its life. However, in places like Montana, whitetail bucks can reach 8-10 years of age. There are many more animals for predators to feed on out west and a lot less pressure from other deer.
Then we look at states like Iowa who have managed their deer population for whitetail with the intent of setting records. The deer there has a history of growing to massive and healthy sizes. Mature bucks being sometimes 8 years in age. Nebraska can also claim to have an abundance of trophy-sized and aged whitetail.
Deer back east also have the increase of the human population to consider. People and deer encounters have been on a steady incline over the years. More and more people are reporting motor vehicle accidents involving deer.
Deer often get caught in combines and other farming machinery during harvests. This accounts for the much younger age of whitetail deer in the eastern part of the United States. This is also the reason for their small size. The larger an animal population is feeding off limited resources results in smaller animals. These smaller deer are more prone to injury, disease, and being a meal for a coyote.
Mule deer tend to live to the age of 12 and above. It is no surprise that these deer would have a much longer lifespan than their whitetail cousins.
Mule deer often live in rugged areas that are harder to reach. They like to stick in higher elevations. When found in the mountains and the high desert, you will find them living among the bighorn sheep.
Since they have a penchant for living in remote locations, they will have a lot more access to protection. So it’s not totally uncommon to see mature bucks in the mule deer family getting up well over 10 years of age.
It is not just food that comes into play. Predators play their part as well. In areas where predators are not managed as often, the deer have a much shorter lifespan. Some areas have out of control predator populations with surges in both feline and canine predators.
For example, a mountain lion needs to eat at least one deer a week to sustain its life. A cat will generally kill that one deer and hide it to return and feed on other days. If a cat kills a deer in an area with a large coyote population, the cat will be forced off its kill eventually. The coyotes will feast on the kill, and the cat will have to take another deer to survive.
At some point, the same cycle repeats itself, and the lion has to kill another deer, and so on. Soon this cat is now killing 5-7 deer a week to keep pace with the packs of coyotes. This is why it’s important to take an active role in predator management. Either by trapping or hunting these predators.
Diseases also play their part in wild deer populations. Areas with a higher population of deer have an increased risk of disease. Some areas once boasted much larger deer populations but have had heavy hits due to bluetongue disease and chronic wasting disease.
More wide open and less populated states have not suffered as much damage from these diseases. You see whitetail populations dealing with the brunt of these diseases far more than their western counterparts.
Mule deer populations are more spread out and aren’t as densely populated as whitetail deer areas. Mule deer like the high country and more remote areas. In comparison, whitetail deer prefer lower elevations and being near water. However, the damage can still take many forms.
Bluetongue disease managed to jump to the pronghorn populations out west from deer, driving those numbers down quickly. Diseases are the largest killer of deer populations than all the other factors combined.
For decades now, every state’s Fish and Game offices have worked with hunters and conservation groups. They intend to extend the lifespan of deer species so that they can grow to their fullest potential. Some states have an easier time than others with the regulation of their deer populations.
It is a daunting task that often fights both science and public opinion. Sooner or later, an equilibrium will be struck, and balance comes. Sometimes through science and other times through blind luck.
“How long do deer live?” is not just a simple question with a simple answer. There are just too many factors involved.