Studying White-Tailed Deer in the Digital Age

Only hours old, a fawn curiously peered upward as people approached. Hands pulled the grass back from the fawn’s hiding place on this spring day, its mother likely watching somewhere beyond the woodland’s shady edge. A radio collar that researchers placed on the doe the winter prior transmitted a signal to a satellite in space, which relayed the doe’s location to a computer, enabling the biologists to search the general area and find the fawn hidden in the grass. Now, the fawn will also be followed via radio telemetry in a broad study to keep Missouri’s deer herd healthy.

Biologists from the Missouri Department of Conservation and the University of Missouri–Columbia (MU) are using high-tech gear to peer into the daily world of white-tailed deer. They’re two years into a five-year study of deer reproduction, movement, and mortality. One study area is in north Missouri farm country, while another is in the timbered hills of the southern Ozarks. Those areas represent much of the state’s ecology. The project is funded with assistance from Federal Aid in Wildlife Restoration Funds.

“By the end of this study, these data will give us a very clear indication of what deer are doing in Missouri,” said Jon McRoberts, an MU research scientist and project coordinator.

A History of Research

The Department has always tracked the state’s deer herd with studies and harvest data. Science-based conservation helped whitetails rebound from the state’s low in the 1920s of 400 deer in the Ozarks. Now, deer are enjoyed statewide by both wildlife watchers and hunters. Deer hunting is a tradition valued by families, and it pumps more than $1 billion annually into Missouri’s economy.

The state’s most recent detailed deer studies were conducted in the 1980s and 1990s. Since then, new technology, such as GPS collars, makes monitoring deer movement more accurate. Also, deer habitat has changed in some regions, said Barbara Keller, Department resource scientist. Deer populations are down in some areas due to habitat changes, harvest, or disease. However, in other areas deer numbers are on the upswing.

“We need to update our deer survival and reproduction research and plug that information into a new population model,” Keller said. “We’re also looking at deer habitat use and their movements, which could affect disease management. We’re learning how deer use the landscape in different areas of Missouri.”

The Five-Year Study

As part of the five-year study, researchers are trapping and monitoring deer in portions of Nodaway, Gentry, Andrew, and DeKalb counties in northwest Missouri where crop farming is prominent. Timber and cattle are produced in the study area of the Ozarks that includes parts of Douglas, Howell, Texas, and Wright counties. Farmers are key partners because most of the study is conducted on private land.

“We appreciate the cooperation of the landowners,” said Vance Vanderwerken, the northwest MU research team leader. “We have 120 landowners assisting in our area this year and last.”

In the Ozarks, more than 150 landowners have cooperated with the team’s trapping, searching for fawns, and recovering mortalities, said Ozark team leader Billy Dooling.

The study could not happen without these landowners providing access for trapping and monitoring deer, Keller said.

“People are interested in the study,” Keller said, “and we’re very fortunate they are.” Research teams trapped deer early in 2015 and this January into March. Summer began with 177 adult deer being tracked via the GPS collars and computers.

To Catch a Deer

Teams use traps or rocket nets to catch deer. The traps are small pens made with metal frames and woven net. Deer can enter but cannot leave. Team members quietly approach the trap, pull some pins, and collapse the netting on the deer. They subdue the animal and take measurements such as neck size, hind foot length, eye-to-nose distance, and chest girth. Blood samples are also taken and later frozen for possible future research studies.

A battery-powered GPS collar is placed on the neck of each adult deer. Every five hours, the collar takes a reading by satellite of the deer’s location. That data is transmitted at four-day intervals and stored on computers. Female deer receive extra attention during the trapping. Crews use an ultrasound unit to tell if a doe is pregnant. A blood sample is also taken as backup. If the doe is pregnant, a vaginal implant transmitter (VIT) is inserted. This transmitter sends a radio signal that crew members can pick up with a receiver.

In May and June, when fawns are due, the GPS units on does begin to take readings once an hour and transmit them twice a day to a computer. Biologists watch the GPS readings on a computer, and they know when a doe stays in one spot she is ready to give birth. After a fawn is born, the VIT is pushed out and temperature change causes its radio signal to change. Teams follow the signal to the birth site. From there, team members fan out and search for the fawn. It’s often hot, sweaty work pushing through thick brush or tall grass, but their reward is finding a tawny miracle with white spots, too new to the world to be afraid.

The Search for a Fawn

“Fawn,” shouted Jacob Peterson, an MU research technician, walking fields in a search line last May.

Team members gathered around the fawn’s hiding spot in a brushy draw. The doe had hidden it near a small creek that wound through fields in northwest Missouri. They placed a cloth over the fawn’s eyes to keep it calm during measurements. The tiny deer weighed almost 8 pounds. A small, expandable radio collar was placed around its neck.

Technicians track collared fawns daily to determine if they survive hazards, such as bad weather and predators. Forty fawns in each study area were collared this year. “It’s very important to know our fawn survival rate,” Keller said. “That’s one of the most variable factors within deer populations. Adult deer survival rates are fairly stable. Fawn survival and reproduction are always the most variable.”

Mortality data is useful for this study. Crews sometimes find dead fawns, and adult deer with GPS collars are often located after they’ve been killed by predators or by accident. Hunters are encouraged to harvest deer with GPS collars if that deer is one they would normally take by legal hunting methods. Hunters killed 15 collared deer during the 2015–2016 hunting season. One was taken with a bow and the others with firearms.

“Harvest season went well,” McRoberts said. “Hunters were cooperative and interested.”

On the Move

A few deer in the study have surprised researchers. Most deer stay within a small territory, rarely traveling more than a mile or two or less. But some deer make crosscountry treks. Dooling said one yearling buck in the Ozarks was harvested by a hunter 14 miles from where it was trapped.

“We’ve seen one doe in northwest Missouri that moved more than 15 miles in a week or two and then came back almost where she started,” McRoberts said. “We can’t say why she did it, but to have those kind of data is quite interesting. We were somewhat surprised at how quickly she did it.”

The Goal of the Study

A vast amount of deer data is being gathered, stored, and analyzed. This information will be used in the years to come, along with harvest numbers, to gauge deer numbers in local areas and to forecast future trends. When summer began, the GPS collars had already provided 350,000 data points.

The overall goal of the study is a healthy deer herd in balance with nature and people. Data from the entire study will help wildlife biologists make decisions about hunting seasons and how to respond to a disease outbreak, such as chronic wasting disease.

“It’s really a great project,” McRoberts said. “Landowners text me weekly asking, ‘what’s new.’”

The Five Year Study 2014–2019

• Studies deer reproduction, movement, and mortality
• Focused in north Missouri farm country and timbered hills of the southern Ozarks
• Data collected will help wildlife biologists make decisions about hunting seasons and how to respond to a disease outbreak