Updated: February 8, 2016, 12:12 pm
Collecting good, scientific data is essential to understanding Utah deer.
HOW MANY deer fawns die in Utah each year? And what's killing them? How about the number of deer that are hit and killed by cars each year — do the statistics the state has give an accurate picture of the number of deer that are actually hit and killed?
Fortunately, in just a few short years, all of us — wildlife biologists, hunters and non-hunters alike — will have a much better idea. The Division of Wildlife Resources has started, or is in the process of starting, several mule-deer related research projects across Utah. Examples include the following:
Having plenty of female deer in Utah's population — both adults and fawns — is the key to growing the state's deer herds.
So just how many of the female deer in Utah's population die each year? A study the DWR started in 2009 is already providing some tentative answers.
The study began in December 2009 when biologists placed radio collars on 210 adult does and 210 female fawns after using helicopters to capture the animals.
Placing the collars has allowed biologists to track the deer the collars were placed on. If a collar stops moving for an extended period of time, the collar sends a mortality signal to the biologists.
That signal lets the biologists know that the deer has died.
Anis Aoude, big game coordinator for the DWR, says determining how the animals died isn't the focus of the survey. Some of the areas where deer die are remote — getting to the animal quick enough to determine the cause of death would be difficult and expensive.
"What the study will tell us, though," Aoude says, "is the percent of does and fawns that die in Utah each year."
Biologists collared the deer on seven areas in Utah. (Biologists refer to these areas as units.)
The seven areas — the Cache in northern Utah, the South Slope in northeastern Utah, the Oquirrh-Stansbury and Manti, Wasatch in central Utah, the San Juan in southeastern Utah and the Monroe and Pine Valley units in southwestern Utah — were chosen because their habitat and other characteristics are representative of the areas that surround them.
As biologists compiled results from the first year of the study, they discovered that while 86 percent of the adults survived, only 52 percent of the fawns did.
"We expected fawn survival to be closer to 60 percent," Aoude says.
Aoude cautions that the 52 percent fawn-survival rate is based on only one year of data. "Fawn survival is affected by factors that can vary widely from year to year," he says. "Once we have three to four years of data, we'll have a much better idea how many fawns we're actually losing each year."
Aoude says the DWR should be able to collect data for at least three to four years — and hopefully longer. "The study is expensive to conduct," he says, "but we want to keep it going as long as we can."
In winter 2011, a total of 210 additional female fawns were collared as part of the study.
Aoude says it cost the agency more than $381,000 to buy the collars and do the work necessary to get the study started. It costs about $224,000 a year to keep the study going.
Why do deer fawns die?
So what's killing deer fawns in Utah? A study the DWR is starting will provide some answers. The DWR has partnered with Utah State University and Brigham Young University to conduct the study.
Researchers will conduct the study on the Monroe unit in southwestern Utah. The study will focus on two things — determining why deer fawns die and the role coyotes may have played in their deaths.
Biologists will place a vaginal implant in does they capture on the unit. When each doe gives birth to a fawn, the implant will fall to the ground with the fawn. The implant will send a signal to biologists that a fawn has been born and where the fawn is located.
Biologists will then visit the fawn and place a neck collar on it that will allow the biologists to locate it.
(The specially designed collar will expand as the animal gets bigger.)
After placing the neck collar on the fawn, the biologists will pay a quick visit to the fawn — every other day — to see how the fawn is doing.
If the fawn dies during that time, its carcass will be collected and a necropsy performed to determine why it died.
After the fawn reaches about two months of age, the biologists will cut their visits back to about once a week. Eventually, the biologists will visit the fawn about once every other week. When the fawn reaches six months of age, the visits will end.
"This study will provide valuable information about what why fawns die in the state," Aoude says.
A second part of the study will provide information about the effect coyotes have on deer fawns and whether or not coyotes can be successfully controlled. The coyote portion of the study will run as follows:
During the four-year study, biologists will compare the number of fawns that survived when coyote control was intense with the number that survived when coyote control was less intense.
The study will help biologists learn two things — the affect coyotes have on deer fawns and whether intense efforts to control coyotes work.
In 2008, contractors working for the Utah Department of Transportation picked up more than 4,800 animals on highways across Utah.
Most of these animals were deer. In 2009, they picked up about 4,800 more.
A total of more than 9,600 animals in two years is a lot of animals. But were the animals the contractors picked up all of the animals that were hit and killed by cars on those roads in 2008 and 2009? Is it possible that the contractors missed some of the animals that were killed?
And what about animals that were hit by cars but wandered away from the road before they died — how many animals fall into that category?
A new study will give biologists some answers. The study, which will cost about $364,000 each year to run, will run for three years.
Done in partnership with Utah State University, the first part of the study involves college students riding all terrain vehicles along the edge of roads. When the students find a dead deer, they'll attach a colored zip tie to the animal.
When contractors come along later to collect the deer, they'll log the number of deer that have zip ties on them. This data will allow USU researchers and DWR biologists to compare the number of deer the contractors found with the number of deer they didn't find.
Fifty one locations, each of them about three miles long, will be sampled during the study. The 151 miles that are part of the study represent 9 percent of the total area covered by the contractors in Utah.
"The data we collect will allow us to provide a solid estimate of the number of deer that contractors missed on the roads that weren't part of the sample," Aoude says. "That data will provide a clearer picture of the number of deer that are actually hit and killed in Utah."
The second part of the study will help biologists learn several things, including how many deer are hit by cars but wander away from the road before they die.
In December 2010, collars with global positioning satellite units on them were placed on 31 doe deer near an area of U.S. Highway 6 that deer cross heavily.
(Collars were placed on deer on both sides of the highway.)
The study, which will conclude in May 2012, will help biologists learn where deer cross the highway, how often they cross it, how often they use a wildlife crossing structure that's in the area, and how many deer are hit by cars but die away from the road.
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