How do whitetails cope with extreme weather events?
Ice-covered branches crashed to the ground like chandeliers falling on a marble foyer. With each passing minute, the limbs in the forest in front of me grew heavier as rain fell and then froze on everything it touched. By 4 p.m., a half inch of ice coated the southwestern Missouri landscape.
I was safely tucked into a box blind 80 yards from the trees, peering through a narrow opening in the window, which was frozen in place.
As ice thickened on the world around me and limbs fell with increasing frequency, deer started appearing at the edge of the trees and in the fields.
A small 8-pointer ambled across the open pasture behind me, unsure of his destination. Next, a pair of does trotted out of the frozen forest and just stood in the field, confused about their next move. So did a handful of other deer, including what turned out to be a heavy-antlered 13-pointer that walked out of the timber and stopped well within range of my CVA muzzleloader.
THE ICE FACTOR
There’s no question the ice was forcing the deer to abandon the security of the woods.
The steady, cold rain also meant they needed to eat, said Kansas Whitetails owner Gene Pearcy. He’s hunted through a dozen or so ice storms in Kansas and Missouri during his long career, and his hunters have killed some impressive bucks.
“Some of my most successful hunts are during extreme weather: cold, snow or ice,” the outfitter said. “Deer need to eat more when the weather is bad.”
As I learned last December, it can also push them out of thick cover during legal shooting hours. Pearcy says any foul weather is a good time to be in or near the woods, but ice storms tend to be extra productive.
“You need to be in your stand if you can get there safely,” he said. “Of course, you don’t want to be in the woods because of all the falling limbs, but you’ll see a lot of deer during an ice storm.”
Ice storms might be a great time to hunt deer, but they usually don’t last long. Aside from broken limbs and perhaps some downed power lines, any evidence of the event fades as the ice melts. They don’t seem to bother whitetails much, either, except for the temporary disruption of their routines.
One ice storm won’t make deer starve, nor do they suffer from the weather itself. They simply wait for warmer temperatures to expose food, or they eat through the ice that coats it.
Hunters tend not to worry about whitetails as much in the summer, but deer have a much more difficult time coping with drought.
No weather phenomenon is more detrimental to whitetails, and a host of other wildlife, than long-term drought.
Some regions, including parts of Kansas, are experiencing their worst dry spell in decades.
The Kansas Department of Wildlife, Parks and Tourism cut all antlerless tags in southwest Kansas and other drought-stricken areas.
“Hunter success rates were down, and there seemed to be a decline in fawn recruitment as a result of the dry conditions,” KDWP deer project leader Lloyd Fox said. “However, the decline wasn’t nearly as dramatic as we expected it to be. We wanted to be conservative, just in case.”
Drought can be devastating to fawn survival, though. Caesar Kleberg Wildlife Research Institute scientist Dr. Charles DeYoung says fawn recruitment rates in parts of South Texas were almost zero during the most extreme periods of that state’s drought. A survey on one ranch found just five fawns per 100 does.
Fawns aren’t succumbing to dehydration. The problem, says DeYoung, is that does simply can’t produce enough milk to feed their young. Research has shown the milk is just as nutritious during a dry spell as it is under normal precipitation levels. However, the fawns can’t get enough milk to survive. Others are unhealthy before they are even born.
“Low birth rates have the biggest impact on fawn survival,” DeYoung said. “And if a fawn starts out unhealthy, it likely won’t survive extreme weather.”
Neither Fox nor DeYoung know how often deer must drink or how far they will travel to get water, but windmills and other man-made water sources are generously scattered throughout much of South Texas. Even the parched regions of Kansas have irrigated fields where deer can find adequate moisture.
“Adult whitetails seem to survive even extreme droughts,” DeYoung said.
In regard to antlers, Fox said he doesn’t know if average antler scores decline during dry years in Kansas, but research in Texas points to a decline of as much as 10 inches.
Instead of putting energy into growing antlers as they would during a normal year, bucks experiencing drought use that nutrition to maintain body condition. Antler growth is always secondary to survival.
Too little rain is bad, but what about too much?
University of Arkansas-Monticello professor of wildlife ecology Dr. Don White Jr. says too much water isn’t good either.
He didn’t set out to study the impact of floods on white-tailed bucks, but thanks to a 500-year soaking, he got plenty of data.
He and his colleagues placed GPS tracking devices on 18 antlered bucks and one doe in a study designed to learn more about habitat use in land between the Mississippi River and the surrounding dike on Arkansas’ Choctaw Wildlife Management Area. A record flood changed the study’s focus.
“We thought the potential for flooding might allow us to see how deer respond to such an event, but we certainly had no idea what was in store,” White said.
The Mississippi not only spilled over its banks, but it also rose more than 13 feet above flood stage and killed eight people in Arkansas alone. As White learned, it also took a toll on wildlife living near the river. Of the 18 bucks he was following with GPS signals, five drowned.
“All five were yearling bucks,” White said. “I assume that was related to their lower level of experience in their home ranges, but we really can’t say for sure.”
The rest of the bucks made a beeline for higher ground prior to the river reaching flood stage, moving westward up and over the levee at least 3 miles. A few traveled 5 miles. They stopped when they reached large blocks of timber that served as suitable cover.
“Pretty much all of the ground they crossed was dry, but it didn’t have much cover,” White said. “They were looking for something in particular.”
The flood took place in the spring of 2011. Had it occurred in the fall or winter, White thinks the bucks would have had little chance of surviving. Whitetails are vulnerable any time they leave the comfort of their home ranges. That’s why some states, including Arkansas, sometimes restrict deer hunting during a flood.
In addition to drought, ice and floods, many whitetails in Northern climates live through extreme cold and weeks or even months of chest-deep snow. Like other extreme weather events, snow can be deadly.
High winter die-offs are somewhat regular occurrences in Maine and other northern states where temperatures frequently dip below zero, and deep snow can bury food for weeks.
Things were so bad the last two winters in Wisconsin, the Department of Natural Resources is eliminating antlerless tags in the northern third of the state this fall.
Upward of 40 percent of juvenile deer fitted with radio collars in that region perished from the bitter cold and deep snow. The severe winter weather didn’t loosen its grip, either. Snow blanketed the ground well into the early spring.
Conditions were similar in Maine, where winter kills are a regular occurrence. Portland got 79 inches of snow last year, 27 inches above the long-term average annual snowfall. Temperatures were far below average, too.
The state lost an estimated 14 percent of its deer herd. As a result, the Maine Department of Inland Fisheries and Wildlife reduced the number of deer tags by more than 9,500.
It’s not so much the cold as it is the deep snow, says MDIFW deer project leader Kyle Ravana. Whitetails evolved to handle severe cold, thanks in part to a thick coat and abundant fat reserves. The problem comes later in the winter when those fat reserves are depleted and food is scarce.
“Deer basically go into controlled starvation in northern ranges,” he said. “They will eat, but they aren’t adding anything to their fat reserves. They also gather in what are called deer yards, which are usually in thick stands of conifers. Yards can range in size from 20 to 1,000 acres. The conifers hold snow on their branches, so it’s not quite as deep on the ground, but there is little in the way of food. What is available gets eaten pretty quickly.”
Like drought, extreme winter weather is hardest on fawns. Ravana says young deer tend to enter the winter with less fat than adults, and they have a higher metabolism. They use up their limited fat reserves quickly.
Extreme cold and deep snow also lead to lower fawn production the following spring. Does go into the fawning season in poor shape and give birth to unhealthy fawns that are less likely to survive into the next winter.
“Whitetails can bounce back from one severe winter fairly quickly, but two in a row can be real hard on them,” Ravana added. “We had two bad ones in 2008 and 2009 and lost at least 35 percent of our deer population.”
The good news is that Maine’s deer will recover. So will whitetails in other states where hard winters, epic droughts or floods have taken a toll.
Severe weather might knock down deer temporarily, but they always manage to pull through even the most extreme conditions.
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This article was published in the November 2014 edition of Buckmasters Whitetail Magazine. Subscribe today to have Buckmasters delivered to your home.