Watching over the herd
Grand County is known for an abundance of natural wonders such as high mountain peaks and beautiful river valleys. Among our most prized assets is our wildlife that brings both beauty and economic vitality to many areas of the high Rockies.
Every year thousands of hunters from throughout the state and nation ascend the mountain passes to the high country in search of big game like elk and deer. The number of hunters is determined primarily by the number of licenses issued by Colorado Parks & Wildlife (CP&W), the agency that oversees and manages the state’s wildlife resources. The number of licenses issued varies year by year and is determined by CP&W based primarily on population studies of big game herds throughout the state.
Kirk Oldham is a wildlife biologist for CP&W and is based out of the agency’s Hot Sulphur Springs office. Oldham oversees the mule deer population/mortality study for CP&W for the Middle Park mule deer herd. Oldham has worked for CP&W since 2000, spending his entire career with the agency within Middle Park. He was the District Wildlife Manager for the Grand Lake and Granby area before becoming the department’s local wildlife biologist and he is intimately familiar with the Middle Park mule deer herd.
Oldham and other wildlife biologists study big game herds in specific locations in Colorado. For mule deer populations CP&W monitors five different herds that operate in five unique ecotypes throughout mountains. Middle Park is home to one of the five herds used for monitoring mortality and population levels.
The other four herds monitored by CP&W are: the Uncompahgre Plateau herd near Montrose, the Salida area herd, the White River herd in the Meeker area and the Gunnison herd, which CP&W first began monitoring in 2008. The herds that are selected for mortality studies live within unique ecotypes in Colorado, or regions with unique ecological factors such as climate and vegetation.
Parks & Wildlife considers the five different herds as relatively representative of the different ecotypes across the state in which various herds of mule deer live. “We take any herd in the state and apply numbers from these herds to other herds,” Oldham said. “We don’t have the resources to monitor every deer in the state. That is why we apply those survival studies to other herds.”
Parks & Wildlife views all mule deer within Middle Park as part of the larger Middle Park herd, which stretches from Grand County down into Summit County. “We don’t have a specific Fraser herd,” said Oldham. “It is all one herd. The management goes all the way back to the fifties.”
The ongoing survivability study of the Middle Park herd grew out of a much older population study conducted on the mule deer in Middle Park beginning back in 1954. “At that time we did a live deer count in February,” Oldham explained. “We would get volunteers, college students and staff and count every deer would could on cedar ridge, south of Hot Sulphur Springs. In May we would count dead deer on cedar ridge. It would give us an idea of the mortality and we would apply those numbers to all of Middle Park.”
Since then technology has advanced and new methods of gathering data were taken up in favor of the older method of counting deer on cedar ridge. Prior to the end of the study the cedar ridge mule deer population count was the longest running wildlife census in the nation, according to Oldham.
Tthe ongoing population and mortality studies conducted by CP&W are a key component of the state’s management of mule deer and, “allows us to appropriately set harvest numbers,” he said. “The purpose of intensively monitoring these deer herds is to monitor deer survival, adult survival and fawn survival.”
The current mule deer study in Middle Park originated in the late 1990s and utilizes radio collars on a sample of 90 mule deer adults and 60 fawns along with physical counts conducted by Oldham and other CP&W employees from the air and on the ground. For several years after the study was initiated only fawn and doe survivability were monitored but starting in 2011 CP&W also began monitoring buck mortality.
Each year in December or January CP&W employees head out into the field and capture local mule deer to be fitted with the collars. Every week Oldham and others reexamine data from the radio collars, which give off a mortality alert if the collared animal does not physically move for a specific period of time.
After Oldham receives a mortality signal from a collar he or others from CP&W physically go to the location of the collared animal to determine if indeed the animal has died and if possible what was the cause of death. “Depending on how soon we can get to it we can determine time of death and cause of death,” Oldham said. The collars themselves are solar powered and do not need batteries.
Primary causes of mortality in Middle Park vary but according to Oldham, if you look over the entirety of the study going back to 1998, there is a relatively even split between road kills, starvation and disease deaths and predator deaths. Oldham pointed out that CP&W’s mortality studies do include hunter harvests into their figures.
So far in 2016 mule deer populations in Middle Park are at a 90 percent rate of survivability roughly overall. “It fluctuates,” said Oldham. “That is why we monitor. It is high for this time of year.” Fawn survivability so far in 2016 is at roughly 65 percent. “The months of March and April are typically when we see the highest mortality in fawns,” Oldham said. “We expect their mortality to be higher.”
Over the past decade and a half the Middle Park mule deer herd has averaged a survivability rate of 90 percent. The rate of survivability depends on many factors with the intensity of winters being among the most significant. Some winters are particularly harsh and produce outliers in terms of data.
During the 2007-2008 winter survivability in adult mule deer in Middle Park dropped to 79 percent and fawn mortality fell to 32 percent. The 2009-2010 winter, which was much more mild in comparison, saw trends move in the opposite direction with a 93 percent survivability rate for adults and close to 80 percent for fawns.
The current population of the Middle Park mule deer herd is roughly 16,800 with a rate of 49 bucks per 100 does. The population is above CP&Ws population objectives for the region, which is 10,500 to 12,500 mule deer. Population objectives for big game herds are based on carrying capacity, a figure developed by CP&W based on how many animals they believe a specific area can support. Because the Middle Park herd has trended above objectives for the past several years the state is more likely to issue additional game licenses in the area.
“We have had increased opportunity for licenses since 2010,” said Oldham. “There is ample opportunity for deer hunters in Middle Park.”
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