The Truth About How Deer React To Natural Disasters

After major natural disasters, deer populations and habitat see major changes.

April 21, 2023 By Dr. James C. Kroll

We all were shocked by images in the news from the historic tornado that tore through seven states in December 2021. Who could not be touched by scenes of people made homeless by the storm? There also were others made homeless and negatively impacted by this disaster – the many species of wildlife inhabiting the forests laid on the ground that day.

Over the last five decades, we have documented impacts of tornadoes, hurricanes, wildfires and blizzards on white-tailed deer, both directly and indirectly. Our experiences have involved two EF 3 tornadoes, three hurricanes (including Katrina and Rita), one broad-scale wildfire and the “Snowmageden” of Feb. 2021!

The white-tailed deer evolved amongst a highly volatile climate, coming at the end of the last Ice Age. Each species evolves an optimum reproductive strategy that permits them to recruit the optimum number of new individuals annually. There is a reason why does have two fawns, they’re fully “expecting” to lose one of them. The post-partem behavior of does is to hide each fawn in a different location, returning to feed each for only a few minutes. Supposedly, this reduces the scent profile in the area immediately around the bedded fawn. Some predators (such as bears) have countered with an ability to smell some 400X better than a bloodhound! I have pointed out many times that the whitetail doe is one of the few ruminants that has the ability to wean more than her body weight.

Our studies clearly show that whitetails must have at least 40 percent recruitment to maintain normal age structure. Remember, recruitment is not the same as fawn crop. It is the percentage of fawns that live to be one year of age. The breeding ecology of whitetails is geared to being able to saturate their range in five to seven years. Why? Whitetails are a disturbance species, meaning they depend on periodic disturbance for survival. In most of the whitetail’s range, the preferred habitat involves either trees or brush. In many areas, it takes no more than seven years after a disturbance for the deer forage to grow above the “deer zone.”

Further north, that time may be up to 12 years; yet, whether it be seven or 12 years, deer only have a short time to take advantage of a disturbance. As habitats mature, the carrying capacity drops dramatically, meaning deer must exist at very low densities. Once a disturbance happens, the flush of deer foods allows them to rapidly increase, which results in natural selection for the ones that could survive under less than optimum conditions. This goes to show that a disturbance’s effects on wildlife aren’t only negative. What is considered a disaster to humans may or may not be to species such as whitetails. Obviously, as noted above, they benefit from periodic disturbances. However, that does not mean there is not an immediate negative impact from a particular catastrophic event. Impacts are separated as immediate impacts or long-term impacts. Let’s take a look at some of our experiences.

TORNADOES

A “normal” tornado tends to follow a set path across the landscape, oft en skipping up and down as it travels. That leaves a series of swaths, broken by undisturbed areas where the tornado raised above the ground.

The width of damage is variable, but usually in the range of one-half mile to a mile. Th e average width of a tornado is about 150 meters (ca. 500 feet) wide and 5 miles long. The longest continuous tract of the December 2021 tornadoes was 166 miles, and as wide as one mile! That translates to a destruction field covering some 106,240 acres of human habitations and wildlife habitats.

My good friends, Larry and Tyler Porter, have a great hunting operation out of Dawson Springs, Kentucky. They know first-hand the destruction that can be experienced by a tornado of the magnitude that destroyed that 200-year-old town. The area is a mosaic of agricultural fields in flat areas and magnificent hardwood stands in the drainages. Larry and Tyler of Ken-Tenn Hunting are one of the best deer management teams in that area. Tyler told me recently that he really does not know what to say about it. Trees were bent and broken halfway up the trunk, young tree plantings wiped clean and food plots are littered with debris.

“This is really new to us,” Tyler says. “But, whatever it takes, we will do the best we can to make the lives of our deer better!”

HURRICANES

As noted, we’ve dealt with three hurricanes near the Institute for White-tailed Deer Management and Research here in Nacogdoches, Texas; all category three or four storms. As director of the Columbia Regional Geospatial Service Center, I knew quite well the extent of damage to the forests of eastern Texas. After Rita, we had several billion board feet of timber on the ground, looking like a crazy game of pickup sticks! There was so much down timber, the deer could not move around in what had been woods.

On our research facility, we had one of our best bucks killed by a falling tree, and we directly observed many dead deer in the downed forests around us. I have had the unpleasant experience of watching deer during such an event, and they literally go crazy trying to find shelter. Some find their way to deep walled creeks and take refuge in them. One thing is certain, deer have dealt with these problems for millennia, and they find a way to survive. We monitored the damaged forest areas for several years after the hurricane, and the net result was an improvement in overall forage conditions — just like a clear-cut or thinning — but, there is no way to speed up reforestation by mast-baring trees.

In prehistoric times, these events were how the forests became patchworks of different aged trees, so I conclude disasters are an agent of diversifying ecosystems.

During the millennial drought of 2011, much of Texas was damaged by wildfires. One came as close as a half-mile from our research facility, and we were only saved by a river! Fire always has been a significant agent in ecological succession, and many plant communities are preadapted to fire. The wildfires we see in California are catastrophic to people, but they really are natural phenomena that have gone on for millions of years. In deer management, we take advantage of the benefits of fire by conducting prescribed fires to keep deer foods close to the ground and nutritious.

The Native Americans knew quite well the benefits of fire, and regularly burned the forest to improve game production. However, when these fires occur as a result of man’s lack of management, the damage can be quite different. I remember being in North Carolina in 1985 when one of the great Pocosin Fires occurred. Earlier, in 1955, there was the Lake Phelps Fire in Tyrrell, Hyde and Washington counties. High winds carried the fire rapidly over the landscape, scorching some 203,000 acres. In 1985, the Allen Road Fire burned almost 95,000 acres, killing an estimated $30 million in timber. Even worse was the fact this fire burned deep in the ground among the rich peat deposits that characterize a pocosin! The fire killed many deer, and I remember walking through the woods and seeing poor deer standing dazed with burned feet and legs!

During another drought in 2008, there was the Evans Road fire that consumed 40,000 acres and damaged critical wildlife habitat in the Pocosin Lakes National Wildlife Refuge. Despite the destruction, whitetails thrive in these areas today. In the late 1800s and early 1900s, lands denuded of trees by logging burned for days and weeks in the Great Lakes states. The most notable were the Thumb Fire of 1881, Great Hinckley Fire of 1894, Baudette Fire of 1910 and the Cloquet Fire of 1918. These forever changed the species composition of the forests of that region. They were the origin of the large stands of oaks that now are growing old and diseased, where once most of the forest was conifers. In years following, deer numbers exploded, and some of Michigan’s largest bucks came from that time.

No doubt, at the time there were many who thought the deer woods were gone forever, but the whitetail prevailed; they always seem to find a way.

BLIZZARDS AND ICE STORMS

In February and March 2021, two of the worst blizzards to occur in the U.S. literally shut down all human activity from the Rocky Mountains west and as far south as Mexico. During Feb. 13-17, 2021, the worst winter storm (named Uri) to hit the southern Great Plains brought death and destruction to millions of acres and thousands of communities. Effected areas extended from Canada south into Texas, and even into northern Mexico. Some 170 million people were affected, at a cost of $195 billion to the U.S., and $1.5 billion to Mexico. It was the costliest natural disaster recorded in the United States!

The March 4, 2021, North American Blizzard brought record-setting snowfall and temperatures to Wyoming, Colorado and then moved westward into the Rocky Mountains. The storm also extended into the Upper Midwest. There were 21 confirmed tornadoes recorded along with the blizzard conditions. Damages to humans were about $75 million.

These storms not only wreaked havoc on human populations and property, but deer and other wildlife populations are known to have experienced a significant decline. Again, we experienced losses here in eastern Texas at our research facility. We found two bucks that apparently had frozen to death over the week-long period of subzero temperatures. Southern deer are not adapted for handling that kind of weather.

One of our mature bucks met his end during the blizzard, when he tried to squeeze between two trees and wedged his hips between them. The poor buck froze to death before we found him! Interestingly enough, a pair of gray foxes constructed a burrow near his body and fed off him during the last part of our winter. However, it was heartbreaking to find him there, and to visualize what a sad end the buck had.

Natural disasters often are devastating to humans, destroying property and lives. Yet, natural disasters also affect wild animals, such as white-tailed deer. However, just like humans, wildlife manages to survive and rebuild their populations, and they have for millions of years. We tend to think of nature in the here and now, yet nature thinks in the terms of millenia! A 100-year-old oak stand destroyed by the tornado near Dawson Springs will not provide the needed bounty of high energy acorns next fall; but the oaks will come back, and the deer will find other ways to meet their needs while the forest returns. This may mean moving to another area, or just substituting another food source.

We can learn from all this, since it clearly demonstrates that nothing is constant, and change is the way of nature. Managing deer habitat is just taking the principles learned from natural disasters and applying them to management. Afterall, the one thing we have is that we can plan, while nature is random.