In 2016, chronic wasting disease was discovered in wild white-tailed deer in southeastern Minnesota's Fillmore County. The recent detection of the disease offers an opportunity to understand the ways CWD may spread across the rolling terrain of this geographically unique corner of the state.
The study is designed to gather data on deer movement and first began in March 2018. During the first season of the study, a total of 109 deer were outfitted with GPS collars.
The study is focused on deer movements because not much is known about how they use the landscape in and around the CWD management zone, which is called deer permit area 603.
Since 2016, 27 deer have tested positive for CWD in and adjacent to permit area 603, the CWD management zone. Movement data will be used to help predict pathways of potential CWD spread and inform future disease management decisions.
Based on preliminary analysis of the data, the average winter home range size was 1.60 km2 for juvenile females, 2.28 km2 for juvenile males and 2.96 km2 for adult males. These winter home range estimates align with our expectations of deer activity at this time of year.
During the spring dispersal period from mid-April through mid-July, 28 percent of juvenile bucks and 40 percent of juvenile does dispersed from their birth range. The longest movement measured so far is that of a juvenile doe that traveled approximately 77 linear miles from where she was collared. The average dispersal distance travelled for juvenile does was 30.4 km (n=8) and 14.6 km (n=8) for juvenile bucks.
When we remove two outliers (does that travelled a linear distance of 64 km and 124 km, respectively), the average dispersal distance for does declines to about 10 km. Only 17 percent of collared adult bucks moved greater than five miles from their winter range.
Current collar statistics [Updated 11/27/2018]
|Age & gender||Number being tracked|
As of Nov. 27, 2018:
- 12 deer have slipped free of their collars.
- 27 collars have been deactivated due to hardware issues. Some of these deactivated collars remain on deer.
- 23 collared deer have died. Hunters legally harvested 11 of those deer.
- Study details
In March 2018, DNR captured deer using net-launching equipment from a helicopter and collared 83 fawns (49 bucks and 34 does), 25 adult bucks and one adult doe.
Seasonally, there are two periods of the year when deer are likely to move long distances. The first dispersal period spans between April and July when adult does have their fawns. During this time, adult does may act aggressively toward last year’s young, causing them to disperse to new areas.
A second period of dispersal occurs in the fall during the rut when aggression toward subordinate bucks causes them to move in search of a new home range.
The GPS collars have a battery life of about two years and will provide researchers with deer locations 12-25 times a day. Each deer will be tracked for as long as the deer survives or the collar keeps transmitting. When a deer's collar stops moving for 12 hours, it notifies DNR staff who will respond quickly. We'll try to find the deer as soon as possible so that tissue samples can be gathered for disease testing and a cause of death can be determined. The mortality information will help inform Minnesota's deer population model.
Hunting is a normal cause of deer mortality, and hunters are encouraged to treat collared deer like any other deer. If you harvest a GPS collared or ear-tagged deer, please call 507-380-1858.
How will the study information be used?
The study, which is funded by Minnesota’s Environment and Natural Resources Trust Fund, is planned to continue for at least two more years. DNR scientists in Minnesota plan to share information about deer movements with colleagues in Iowa, Michigan and Wisconsin. With that information, research and management strategies can be developed that will have a better chance of slowing the disease spread and benefit the long-term health of white-tailed deer.
- Study area
Locations where deer were collared
This study is focused on deer movements in and around the CWD management zone, deer permit area 603. Click the map above to expand it or view an even larger map in a new browser tab. Because much of southeastern Minnesota is private land, DNR researchers are grateful to the landowners who granted access to nearly 68,000 acres for collaring deer in March 2018.
- Movement maps
- Overview map
Where are collared deer moving?
This map shows the movement of deer in the study as of July 23, 2018. Each color represents a different animal. This maps displays 77 of the 88 deer currently collared. Click the map above to expand it or view an even larger map in a new browser tab.
- Deer 157
This map shows the dispersal pattern of a juvenile buck that moves from Minnesota to Iowa in spring 2018, and then returns to his birth range in fall 2018. He was captured on March 18, 2018, approximately 6 miles north of Granger, Minnesota. As of Feb. 8, 2019, this animal (now a yearling approaching adulthood) is still on the air and transmitting locations within Minnesota. Click the play button on the map above to animate it.
Juvenile doe moves 75 miles
This map shows the dispersal pattern of a juvenile doe. She was captured on March 22, 2018, near Forestville/ Mystery Cave State Park. She began moving in early June 2018. As of July 23, she was located near Cannon Falls – a 75-mile trek from where she was captured. Click the play button on the map above to animate it.
- Deer 192
- Deer 143
- Deer 181
- Photo gallery
Deer in the study
Click on the photos below to view larger images of these collared deer. Photographs were provided by landowners in the southeast. If you are willing to share any high-quality pictures of collared deer, please send them to [email protected].
- Hunting & collared deer
Ear-tagged and GPS collared deer are legal for harvest. We ask that you treat the marked animal like you would any other deer. If you would normally shoot the animal, then harvest it. If you normally wouldn’t shoot that animal, then don’t harvest it. By treating GPS collared or ear-tagged deer similar to any other deer, you will provide truthful representations of typical survival.
If you find or harvest a GPS collared or ear-tagged deer, please call 507-380-1858 and report the information. If there is no answer, please leave a message regarding the ear tags or collar number, how the animal died and your contact information. We will need to collect these GPS collars to download additional movement data for the study.
- Get involved
Most of the deer captures occurred on private land with permission from landowners. DNR staff will keep participating landowners updated on how specific collared deer use the local landscape. Broader findings from the study will be shared here as data becomes available.
The DNR is seeking landowners who would like to participate in future collaring efforts. Interested landowners or anyone who has harvested or encountered a dead deer with a collar can call 507-380-1858 or email [email protected].
Why is CWD a concern?
CWD is an infectious neurological disease that affects deer, elk moose, caribou and reindeer. It causes brain degeneration of infected animals and results in emaciation, abnormal behavior, loss of bodily functions and death. CWD is one of the greatest threats to the long-term health and size of Minnesota’s deer population. Studies of CWD-infected deer herds in Wyoming and Wisconsin have shown population declines and fewer mature bucks. There is no evidence that humans are susceptible to CWD, but new guidelines from the U.S. Center for Disease Control and Prevention caution hunters not to eat deer that are known to be infected with CWD.
For more than a decade, the DNR has maintained aggressive surveillance efforts, resulting in more than 64,000 deer being tested for CWD.
The deer movement study is focused on deer permit area 603 and an area that extends approximately 20 miles around its periphery. Permit area 603, known as southeastern Minnesota’s CWD management zone, is being studied because 17 wild deer have tested positive for CWD there since 2016. Movement data will be used to help predict pathways of potential CWD spread.