Deer populations play an important role in maintaining biodiversity levels in the United States. In the late 1800’s, white-tailed deer populations in the United States had been nearly hunted to extinction. The diminished population caused predator populations like wolves and cougars to decline as well. Deer naturally maintain forest overgrowth and are a vital part of the food chain. Luckily, deer have a high reproduction rate, so it didn’t take long to correct the imbalance. Deer populations rebound quickly enough that by the 1950’s regulated hunting practices could be put into use. Today deer populations are under no threat. In some regions of the United States deer have become so abundant that they cause more harm than good.

In New Jersey, deer populations have grown so large that they cause major road accidents, destroy private property, and spread Lyme disease. New Jersey park management departments have turned to hunters to cull deer populations. Deer hunting has proven to have many benefits. Besides controlling the population and spread of disease, it boosts the economy. Some areas of New Jersey will pay hunters to track and hunt deer, while many others require hunters to purchase hunting permits. The purchase of these permits goes towards the maintenance of the state’s wildland properties. The hunters can feed their families, as well as earn an income by selling their deer harvests to licensed butchers. But to make a deer hunting program successful, some towns in New Jersey have turned to drones to get accurate population data.

Earlier this year, Raritan Valley Community College received an anonymous donation of $300,000 to support environmental and biological studies. With the funds, a team of biological research students had the opportunity to test out some new drone equipment at the High Mountain Park Preserve in Wayne. The preserve is one of the largest conserved woodland areas in New Jersey spanning 1,153 acres of land. The preserve is home to 18 rare protected plant species which have become vulnerable from deer eating them. Using a drone with an infrared camera, the students counted an average of 39 deer per square mile of searched preserve land. These numbers are 4 times what is considered to be a healthy population number for the region. The data will be presented to The Nature Conservancy that manages the parklands. The Conservancy will then be able to extend regulated hunting permits to bring the population back within safe numbers.

Meanwhile, in the Northwestern United States, deer populations have began to decline after a series of unusually harsh winters. Deer migrated to the Northwest after decades of logging pushed them out of their natural habitats. A deer’s body, specifically smaller white-tailed deer, is not meant to navigate and search for food through deep trenches of snow. These harsh winters have led many deer to die from starvation or getting stuck in the snow. Wildlife biologists from the Minnesota Department of Natural Resources (MDNR) report that while most in the state won’t notice that there are fewer deer in the area, hunters have seen an impact on their harvest. MDNR biologists have begun several programs to track and balance deer populations.

The key to MDNR’s deer population management program is by tracking fawn development and survival rate. MDNR biologists Eric Michel and Tyler Obermoller have been running the fawn study that is used to determine how many deer are in certain areas. Based on these numbers, parks will have an idea of how many hunting permits can be released each year to maintain a healthy deer population. “Fawn survival is an important component of determining deer populations,” Michel said. “Here in the southwest part of the state, we’re just beginning a three-year fawn survival study using drones to help us find fawns shortly after they’re born so we can get to them and outfit them with GPS transmitting collars.” The fawn collar program is something that MDNR has been practicing for some time now, but it was not always so simple.

Before using drones to track fawns, Michel and his team would have to spend a lot of time and money to get to the fawns. “The old method,” he recalls, “required us to capture does and sedate them to insert a transmitter in them that sensed the temperature change that occurs when a doe gives birth to a fawn. When we received this signal, we had to hurry in and find the fawn and put a collar on her.” Prior to this, MDNR would periodically fly over regions in a small plane or helicopter to take a census of deer. Not only was this extremely expensive and time consuming, but the manned aircraft would also disturb wildlife leading to inaccurate counts. Michel and Obermoller have already found that drones are far more efficient.

Michel explained that after giving birth, a doe will leave the fawn to hide in the grass. After it is born, the fawn has no scent that can be picked up by predators, so the mother can safely go off to forage. She will return every few hours to nurse her baby and move it to a new spot. A predator may not be able to sniff out a fawn hiding in the grass, but a drone with an infrared camera can. Michel and Obermoller survey known deer paths in the early dusk hours when a doe would be out feeding. When the drone’s infrared camera spots a heat signature in the ground that resembles the shape of a fawn, the GPS coordinates are logged.

Michel and Obermoller position themselves close to the saved GPS coordinates shortly before the sun fully rises and the mother returns. Then they fly the drone back to that spot to take a daylight picture to confirm the presence of a fawn. Once they have confirmation of a fawn, they quickly approach the baby resting in the grass. Michel and Obermoller will then weigh and measure the fawn and fit it with a biological transmitter collar. The collars are perfectly harmless to the deer and will remain active for 18 months while reporting data back to the MDNR every 4-6 hours.

Using data collected by the drones and the collars, Michel and Obermoller hope to compile realistic censuses on deer populations. The data will also give biologists an understanding of how deer affect the environment and vice versa, as well as when fawns move off on their own. By applying this type of research the MDNR can safely regulate deer populations. This keeps hunters happy and employed, supports symbiotic prey/predator relationships, and balances ecosystems. This data will also allow the MDNR to set up models that would prevent deer populations from getting out of control like how they have in New Jersey. Michel says that once the drone program has set a precedent in Madelia, MN where he is stationed, they hope to branch out further into the state’s vast forested areas.

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