Supporting DNR’s Response to Chronic Wasting Disease in Southeast Minnesota
By Bob Wright and Julie Hines, GIS Unit, Section of Wildlife, Minnesota DNR
Chronic Wasting Disease (CWD) is an infectious, non-treatable and fatal neurological disease of North American deer, elk and moose. Because of its implications for managing wild populations of these animals, the Minnesota Department of Natural Resources (DNR) has been actively monitoring for the disease since 2002, when it was first detected in captive elk in Minnesota.
The most recent detection (2009) was a captive elk herd located just north of Rochester near Pine Island, which triggered the CWD response plan. The plan calls for 3 consecutive years of intensive surveillance in the area surrounding a CWD-positive captive cervid farm. Thus, DNR began testing hunter-harvested deer in the Pine Island area in Fall 2009. In November of 2009 and 2010, over 3,200 samples were collected from deer harvested by hunters in southeastern MN.
CWD in One Wild Deer Intensifies Need for Surveillance
In January 2011, test results came back positive for a wild doe harvested near Pine Island in 2010, which required additional sampling to determine the extent of the CWD infection in the wild population. These samples were taken from deer killed via shooting permits issued to cooperating landowners, agency-sponsored culling (using USDA-Wildlife Services), vehicle collisions, or otherwise found dead.
A critical first step toward designing this additional sampling effort was to develop an estimate of deer numbers and geographic distribution in the focus area. This was accomplished through aerial surveys that were designed and implemented using GIS and GPS technology, and custom survey software developed by DNR staff. A “quick and dirty” survey of the entire surveillance area was conducted via airplane and a more intensive survey of the core area was conducted via helicopter. Due to the high concentrations of deer detected during the aerial surveys and the unknown prevalence of CWD in the captive elk herd, DNR established a surveillance goal of 900 samples within 10 miles of the harvest location of the positive deer.
Data and Technical Challenges
Land ownership and parcel data: Knowing where both landowners and USDA staff were taking deer was the key to effective field operations, and the specific locations of these activities were constantly changing. This information was also important for creating GPS background maps for field staff and for providing weekly summary maps for staff and the public. The CWD surveillance area covers 4 counties and is dominated by small-parcel private ownership, including the city of Rochester. With parcel data in various formats and the situation on the ground constantly changing, using the parcel data by individual counties proved to be unworkable.
The solution was to develop a single parcel layer stripped to the minimum attributes needed to contact landowners, then to add attributes that documented sampling activities. A spreadsheet version of the attribute table was updated by field staff, then joined back to the parcel layer for developing summaries and updates.
Ever-changing conditions: Overall, the biggest challenge for everyone involved in this project was how rapidly the situation kept changing. However, landowners and field staff rose to the occasion and collected 752 testable samples before deer began dispersing in early April.
Most importantly, none of the deer tested for CWD were positive. Additional surveillance is planned for this fall.
For More Information
Check the DNR’s website for additional CWD maps and information.
Contact Bob Wright at email@example.com or 651-296-3292.
See also previous GIS/LIS News articles: