In 2016, chronic wasting disease (CWD) 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.
A study designed to gather data on deer movement 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, 17 deer have tested positive for CWD in permit area 603. Movement data will be used to help predict pathways of potential CWD spread and inform future disease management decisions.
Contractors used helicopters and nets to capture and collar deer.
- Study area
Each point represents a location where a deer was collared for the movement study. 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.
- Study details
For the study, 83 fawns (49 male and 34 female), 25 adult bucks, and one adult doe were captured and collared using a helicopter and nets.
Seasonally, there are two periods of the year when deer are likely to move long distances. The first occurs between May and June when female deer have their fawns. During this time, adult females 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 collars are designed to expand as animals grow.
The GPS collars have a battery life of about two years and will provide researchers with deer locations 12-24 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. An effort will then be made 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.
Current collar statistics
96 deer are being tracked. These animals include 44 juvenile bucks, 31 juvenile does, 20 adult bucks, and 1 adult doe (updated 5/4/2018).
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 population health of white-tailed deer.
- 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 and moose. 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 Minnesota Department of Natural Resources has been maintaining an aggressive surveillance effort that has tested more than 64,000 deer 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.