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Page last updated on November 23, 2022 at 12:05 pm

The conclusion that white-tailed deer are having a negative impact on plant diversity at Griffy Lake Nature Preserve is based on several sources including:

 

In 2014, Bloomington Parks and Recreation applied for and received from the Indiana Department of Natural Resources a Special Use Deer Control Permit in order to begin addressing the problem of the overpopulation of deer at Griffy Lake. White Buffalo Inc. was selected to provide sharpshooters to reduce the numbers of deer at Griffy. Park and Recreation staff placed bait at selected sites throughout the preserve, but the baiting effort was not successful and no deer were removed. White Buffalo, Inc. provided a summary report for the Board of Park Commissioners, which was presented at the May 26, 2015 regular meeting of the Park Board.

 

The Parks and Recreation Department again contracted with White Buffalo, Inc. in 2017 to conduct a sharpshoot deer cull at Griffy Lake Nature Preserve. The goal of the sharpshooting effort was to remove enough deer from the Griffy Lake Nature Preserve to reduce browse pressure on understory plant species and seedling trees to the point these species are able to recover.

 

Natural Resources Manager Steve Cotter presented a report of the 2017 deer cull to the Board of Park Commissioners at their January 17, 2018 meeting. A Griffy Lake Nature Preserve Deer Management Plan dated December 2017 was also presented to the Park Board.

 

The 2017 deer cull took place over 10 nights between December 15-28. (no sharpshooting occurred between 12/24 and 12/26.) The cull resulted in the removal of 62 deer from the Griffy Lake Nature Preserve; 43 female deer and 19 male deer were harvested over nine days. The deer were processed by KW Deer Processing with financial assistance from Farmers and Hunters Feeding the Hungry. 1,682 pounds of venison were donated to the Hoosier Hills Food Bank. See Deer Herd Reduction at Griffy Lake Nature Preserve Completed for Season.

 

After the 2017 sharpshooting effort, Bloomington Parks and Recreation was invited to apply for a Community Hunting Access Program (CHAP) grant from the Indiana Department of Natural Resources. The DNR created the CHAP to increase hunter access to public properties and to help communities address overabundant deer by allowing closely supervised white-tailed deer hunting in urban environments.

 

Bloomington Parks and Recreation used the grant funding to hire White Buffalo Inc. to coordinate a public hunt at Griffy Lake Nature Preserve over six separate days in November and December 2018. Due to a lack of qualified applicants for the CHAP hunt, no hunt was held in 2018; see Deer Herd Reduction at Griffy Lake Nature Preserve Rescheduled for Fall 2019.

 

The Department received a CHAP grant for $25,000 to conduct a hunt in 2019, and once again contracted with White Buffalo, Inc. to recruit, screen, and manage hunters to participate in the CHAP hunt. A total of 26 deer were removed over six separate CHAP hunting days at Griffy Lake in November and December 2019. 

 

A total of 40 deer were removed from Griffy Lake Nature Preserve during a third CHAP hunt conducted in 2020; the 2020 CHAP hunt was also coordinated by White Buffalo, Inc. A CHAP hunt at Griffy Lake Nature Preserve, held during deer firearms season in November 2021, resulted in the removal of 47 deer from the nature preserve.

 

Background 

History of Deer Population in Indiana

 

Griffy Lake Nature Preserve is one the community's most beautiful and ecologically-diverse areas. Located on the north side of Bloomington, the 1,220-acre preserve includes a 109-acre lake and provides valuable space for hiking, fishing, teaching and research and is home to a rich variety of plants and animals. In interest of protecting the preserve, the City and its partners commissioned the Griffy Lake Nature Preserve Master Plan in 2008. The Plan pointed out that an ever-increasing deer population was stripping the forest understory of native plants and providing the opportunity for invasive species to become established. The Plan calls for further study "to determine whether there is an overabundance of deer and how plant communities respond when the pressure of presumed overabundance of deer is removed."*

 

Researchers at the IU Research and Teaching Preserve for several years used deer exclosures to track the effect of deer on plant communities. These exclosures are fencing units that keep deer out, but allow other plant eaters in. The result of these studies showed that the vegetative diversity at Griffy was declining as a consequence of deer overbrowsing, resulting in an unnaturally open understory.

Presentation by IU Biologists Clay & Shelton -- 07 December 2010

Deer heavily browsed the understory in the foreground in contrast to the exclosure in the background. (Credit: Angie Shelton)
Deer heavily browsed the understory in the foreground in contrast to the exclosure in the background. (Credit: Angie Shelton)


Some of the most notable effects found by these researchers and scientists at Purdue studying the effect of deer browsing on regional forest ecosystems include:

  • Reduced presence of native flora such as hemlock, yellow birch, pines, lilies, orchids, spring ephemerals and smaller plants
  • Reduced ground cover of herbaceous species
  • Reduced regeneration of wood species in the understory
  • Reduced species richness
  • Increased presence of non-native exotics and invasive species
  • Reduced species evenness and diversity
  • Reduced seedlings and saplings
  • Indeed, Griffy Nature Preserve is now dominated by plants deer don't eat: pawpaw, spicebush, white snakeroot, mayapple, jack-in-the-pulpit, many invasives, such as Japanese siltgrass and garlic mustard

Overbrowsing does not just affect plants; overbrowsing:

  • Significantly reduces ground and shrub-nesting songbird habitat and decreases the survival rates of birds such as the woodthrush and Acadian flycatcher, both species that appear to be declining in the Midwest**
  • Reduces habitat for other mammals, reptiles and amphibians
  • Reduces food sources for other herbivores
  • Increases soil compaction
  • Contributes to soil erosion
  • Reduces leaf litter depth

Researchers point out that browsing poses the possibility of producing an "alternate stable state" - a condition in which a forest would never return to its natural state, even if browsing pressure were diminished by a permanent reduction of deer densities.

 

 

*Griffy Lake Nature Preserve Master Plan, Monroe County Indiana, Summer 2008. http://bloomington.in.gov/media/media/application/pdf/3566.pdf , p.58

** This has been demonstrated by Purdue scientists studying the effect of deer browsing on avian communities in Brown County. Griffy is part of the Brown County Hills Sections of the Highland Rim Natural Region. Scientists at the IU Research and Teaching Preserve advise that the studies examining the effect of deer overbrowsing on migratory songbirds can be applied to Griffy. See, Parker, et al., The Influence of White-Tailed Deer on the Biodiversity of Indiana State Parks.