Study update: Winter 2020-2021
- Currently monitoring 45 deer that were collared in 2019 and 2020
- 12 previously collared deer were harvested during the 2020 hunting season
- About one-third of collared deer moved away from their birthplaces
- On average, deer traveled approximately 13 miles to set up an adult home range
- Some “long-distance” dispersers travel great distances: one buck traveled about 54 miles; our longest dispersing doe traveled about 77 miles!
Because chronic wasting disease is spread through a deer’s contact with infectious proteins, called prions, understanding the natural social and movement behaviors of deer gives us a better understanding of how the disease spreads between deer and to other deer populations. This information can help managers predict where the disease might show up next and plan management activities to minimize that spread.
Thanks to funding from the Environment and Natural Resources Trust Fund, the DNR is studying how deer move across southeastern Minnesota, gathering information that we can use to inform how we manage CWD in Minnesota. For example, if we see that deer are traveling along rivers, then we may want to concentrate disease surveillance in areas connected by long river corridors.
Since 2018, biologists have been tracking GPS-collared deer in nine counties in southeastern Minnesota, in areas where CWD has been detected in wild deer in Minnesota since 2016. The study focuses on young deer, around 1 to 2 years of age.
Each winter, the team fits each young deer they capture with a GPS collar and unique ear tags. The collars record the deer’s location every 1-4 hours for up to two years. If a deer stops moving, the team is immediately notified with a text message.
- 26% of does and 43% of bucks moved away from their birthplaces to establish a new adult home range.
- On average, does moved about 12 miles from their birthplaces and bucks dispersed 14 miles away from their birthplaces.
- A few deer appeared to move back and forth between winter and summer home ranges.
- Deer that migrated between summer and winter ranges moved shorter distances; on average does and bucks moved 8 miles and 11 miles, respectively.
- Legal harvest and vehicle collisions were the main causes of death for young deer (1- to 3-year-olds) in our study.
- One 2018 collared doe died by a vehicle collision outside of Preston on Oct. 8, 2020. She tested positive for CWD. Not all deer are able to be tested for CWD, but of the 64 deer we've been able to test, she is the only collared deer we have confirmed with CWD. Fortunately, it appears she maintained a home range of about 1 mi2 east of Preston.
- Why do we study deer movement?
Because an infected deer can spread the disease both through contact with other deer and by shedding infectious prions onto land, we can see how disease might spread throughout the herd by tracking where it moves.
Learn more about how CWD is transmitted in deer in this video:
This video was created by the Minnesota Center for Prion Research and Outreach at the University of Minnesota, with support from the Center for Animal Health and Food Safety. Additional CWD educational materials can be found at z.umn.edu/CWDWatch.
- How does CWD spread through natural deer movements?
Deer have three main movements, and disease can be transmitted in any of these ways. This study monitors three movements:
Map shows Doe 192's movement from her birthplace in Rushford to Wabasha County 37 miles away, which is much farther than most deer's travels.
In spring, many young deer leave their family group to establish their own adult home range. Most deer move about 7 miles from their birthplace, but some travel much farther. These long-distance travelers can introduce CWD to areas that don’t yet have the disease. Using GPS data to capture dispersal allows us to understand pathways of movement (“deer highways”) and predict where CWD might spread in the future.
Doe 192, pictured here, moved from the Rushford area 37 miles to Wabasha County.
This buck expanded his adult summer home range (red outline) to a much larger area in the fall (black outlines).
Bucks expand their home ranges in the fall (rutting season) as they search for female mates.
This buck expanded his adult summer home range greatly during the fall.
Seasonal migrations (transitioning from summer to winter home ranges)
Map shows two deer's movements between Iowa in the summer (orange dots) and Minnesota in the fall and winter (multicolored dots).
Some deer move between summer and winter home range areas to access the best available habitat and food resources. This kind of temporary movement can spread disease between two regions.
Since 2018, we have observed two deer that appear to move between Minnesota and Iowa each year, spending summer in Iowa and then returning to Minnesota during fall and winter.
- What is the timeline of the study?
Date Notes March 2018 First capture season: 83 fawns collared April to June 2018 19 fawns disperse December 2018 14 collared deer legally harvested February 2019 Second capture season: 64 fawns collared April to June 2019 25 fawns disperse December 2019 17 collared deer legally harvested February 2020 Third capture season: 52 fawns collared April to June 2020 Actively monitoring 77 collared deer; 21 fawns dispersed or migrated December 2020 12 collared deer legally harvested February 2022 Project expected to be completed
- Where is the study area?
Locations where deer were collared
This study is focused on deer movements in and around the CWD management zone in a 30-mile buffer centered on Preston, Minnesota. 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 about 72,000 acres for collaring deer in February 2019.
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.
- What kind of deer movement have we seen?
- Overview map
Where are collared deer moving?
This map shows the movement of deer in the study between March 2018 and July 2019. Each color represents a different animal. This maps displays 148 deer who were in the study for 30 or more days. As of August 2019, only 66 animals remain in the study. 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
- Have the collared deer been seen in the wild?
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] .
This study would not be possible without the support of landowners. Since 2018, more than 200 landowners in southeast Minnesota have participated in the study by providing access to over 62,000 acres of land for deer capture, and by sharing photos and other information about collared deer on their land.
Landowners, hunters and the public help us with the study by sharing information about collared deer seen throughout the year, providing real-life visuals to the data we're tracking. Feel free to contact us to:
- Share photos of collared deer on your land
- Monitor and report collared deer if sick or injured
- Call in collars of harvested deer
- Ask questions or share ideas about the project
Email us at [email protected] or call us at 507-380-1858.
This project was made possible by a grant of $449,557 from the Environment and Natural Resources Trust Fund administered by the Legislative Citizen-Commission on Minnesota Resources (LCCMR) and additional funding by the Minnesota DNR.