DNR Uses GIS to Monitor Deer for TB
By Steve Benson, Minnesota Department of Natural Resources
The Department of Natural Resources, Wildlife Section, has been monitoring Minnesota’s deer herd for highly contagious Bovine Tuberculosis (TB). TB was detected on a number of northwest Minnesota cattle farms in 2005 and was subsequently detected in wild deer. Intensive testing of deer has been ongoing for a number of years.
This disease is significant due to major economic effects on the Minnesota cattle industry and potential major effects on the health of the deer population. The 12 infected cattle farms were “depopulated,” and the state lost its TB-free status. This has since been modified to include just portions of four northwestern Minnesota counties. The TB strain has been traced to the southwestern U.S. The cross-species transmission occurs when cattle and deer both feed at unfenced outdoor hay piles. The risk is that TB could be harbored in wild deer, then continue to be transferred back and forth if cattle and deer feed from the same piles.
GIS was used first to map infected farms and the locations of positive deer. A new deer hunting permit area was created, encompassing the TB core area so that deer seasons could be modified to allow intensive hunter harvest. Intensive harvest allows more deer to be tested at deer registration stations and also serves to lower the deer population and reduce the risk of transmission of the disease.
Annual aerial population surveys have been conducted to track the size of the local deer herd. The DNR’s GIS-based DNRSurvey application has been instrumental in providing data for researchers to estimate the herd and plan for reductions. A DNR specialist goes up in a helicopter and uses a tablet PC to record deer locations and numbers, using a moving background map to keep an active visual location reference of sampling units.
Intensive deer harvest was not enough. Hunters simply could not harvest enough deer for the sampling intensity and herd reduction required, therefore, sharpshooters were needed. They used the aerial survey data and specialty maps to set up bait piles and began shooting deer at or near these piles, using GPS to record the kill locations. Even though these crews took hundreds of deer, analysis showed that not enough deer were being taken for culling purposes, and bait piles have only a localized effect.
Over the last two years, helicopter sharpshooters were added to the effort to widen the culling and sampling. These teams also took hundreds of deer. Ground crews had to recover all these deer for sampling. Ground crews and air crews had to avoid trespass, so background maps of restricted areas were added to dozens of handheld and aircraft GPS units, and updated regularly.
In large field operations, Wildlife GIS staff supported ground crews by downloading data from the helicopter GPS every two hours during refueling. After driving to crew locations, deer were assigned to crews, field maps were printed and the waypoints were uploaded to field crew handhelds. This was done from trucks, so all GIS equipment had to be mobile. As they located the deer, field crews captured a second waypoint, on the ground, to backup the helicopter data.
After deer were recovered, they were hauled to a testing site where necropsy teams extracted tissue samples and checked for clinical signs of TB. All deer locations were carefully recorded, and the coordinates became part of the database that tracked all tissue samples. Over 11,000 samples have been collected, identifying 27 TB positive deer. Deer herd culling and testing operations will continue in 2010.
For more information, or to arrange a presentation, contact Steve Benson at: firstname.lastname@example.org or (218) 327-4149.