Establishment of a program to maintain deer in balance with their habitat in Indiana's state parks has required several years of effort by many individuals. Excessive browsing by deer within Indiana's state parks was first reported in 1969 when Dr. Alton A. Lindsey reported damage in Ogle Hollow Nature Preserve within Brown County State Park. DNR biologists were reporting excessive deer number and vegetation damage within the park by the mid-1970s. Four scientists were invited to Brown County State Park in 1990 to assess browsing damage. An immediate reduction of the deer herd was recommended by the scientists following this visit. While this recommendation was not implemented, a Deer Study Committee was formed in 1992 to examine the problem of deer in Brown County State Park and make recommendations to the Commission.
A report was submitted to the Commission in February 1993. The Deer Study Committee evaluated several alternative methods to bring the deer herd into balance with the habitat in Brown County State Park. The only viable methods to reduce deer number were found to be either controlled hunting and/or sharpshooters. Six days of reduction was recommended each year until the herd was reduced to the carrying capacity of the park followed by a long-term maintenance program. The Committee also recommended that an assessment of the condition of the park's vegetation be initiated.
A report on the condition of the park's vegetation was submitted to the Commission in August 1993. This report demonstrated the negative impact that deer were having on the understory of forests within the park. Based on this assessment, a one-day reduction of the deer herd was completed in December 1993, resulting in the removal of 392 deer.
The Indiana State Legislature passed a law in 1995 directing the Department of Natural Resources to take action within any or all state parks whenever a given species was causing or was likely to cause ecological damage. This resulted in expansion of vegetation studies to several other parks in June 1995.
Vegetative assessments and deer control programs were expanded to include most of the state parks from 1993 to 2000. Plant species were identified that provided an indication of vegetative response to deer abundance. Large deer exclosures were placed in each park to monitor recovery of the habitat with and without deer browsing.
Assessment of the condition of the vegetation was used to make an annual recommendation on deer reduction to the Director of the Department of Natural Resources from 1995 to 1999. During this period, the Department of Natural Resources maintained records of the number of deer removed per hunter effort and per square mile of park area. Seventeen parks had had at least one reduction by 1999.
By 2000, it was obvious from the removal data and data on recovery of the vegetation that the removal data was a much more sensitive indicator of deer density than was the condition of vegetation. It was also clear that the removal program was allowing recovery of the park's habitat in those parks with several annual reductions. This led to a recommendation in 2000 to use deer removed/hunter effort or per square mile of park area to determine which parks needed another deer reduction. Condition of the vegetation should be used in those parks that have not had a reduction and to monitor recovery in parks where reductions have occurred. The data indicates that with three to four yearly reductions in a park the number of deer removed will drop to 0.22 /hunter effort or 12 to 16 per square mile and will allow recovery of the vegetation. Therefore, data on the reduction any given year is a better indicator than vegetation analysis for monitoring the deer remaining in the park and provides a tool for maintaining a long-term balance between deer and the park's habitats.
My specific recommendations for long-term maintenance of a balance between deer and their habitat within Indiana's state parks are as follow.
1. Continue annual reductions in state parks until all have deer densities at the long-term maintenance level. This level is best indicated by a deer removal level of 0.22 deer per removal effort and/or 12 to 16 deer removed per square mile of park area. Continue to monitor the recovery of the vegetation within each park to insure that deer are being maintained in balance with their habitat.
2. Deer removal data should be evaluated in February to determine which parks need another reduction. Deer removal that exceeds .22 deer/ hunter effort or 12-16/square mile indicates a removal is needed. This will insure that deer remaining in the park are at a level to allow long-term recovery of the habitat. These criteria may need to be refined and adjusted for individual parks as more data is collected in future years. Annual removal data along with habitat recovery data will provide the information needed to maintain deer herds and insure the recovery of healthy state park habitats.
3. The condition of vegetation in the four parks (Ft. Harrison, Mounds, Ouabache, and Summit Lake) that have not had a deer reduction should be used to determine when to initiate a control program. Park naturalists using indicator plant species, deer exclosures, and color photographs should make an annual assessment of vegetative condition.
4. I suggest that a committee of approximately five experts be established
to
annually review the vegetation data in parks, that have not had a deer reduction,
to recommend when a reduction program is needed. This could include a plant
ecologist from the Division of Nature Preserves, a wildlife biologist from the
Division of Fish & Wildlife, a resource specialist with the Division of
State Parks and Reservoirs, and two appointments from the Indiana Academy of
Sciences.
George R. Parker
Professor of Forest Ecology
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