Upstate New York has a deer overabundance problem.
The subject of conservation efforts after hunters nearly wiped them out in the 1800s and released from predation pressure, deer population numbers have exploded creating conflict with humans and putting important plant species under intense browsing pressure. Dr. Bernrd Blossey and Dr. Paul Curtis at Cornell University’s Department of Natural Resources have created an innovative research program based on long-term monitoring to reduce deer populations and monitor deer impact on important native herbaceous species.
Blossey, who directs the Ecology and Management of Invasive Plants Program, described the difficulties of measuring deer impact across diverse forest types. Many of the existing metrics are either focused on woody and not herbaceous species, require measuring species that may not be present at a site of concern, or are sensitive to deer abundance, not deer impact. In response, they created a new metric based on planting red oak seedlings and measuring seedling predation.
Curtis, who serves as Extension Wildlife Specialist and coordinates the Wildlife Damage Management Program, shared his experience trying to reduce the deer population and achieve measurable results in the vegetation community. Sterilization was one method of population control. However, a reduction in the doe and fawn population was offset by increased populations of stags, leading to no observable reduction in deer impact on plants through their metric.
However, Curtis and Blossey were able to determine that hunting pressure and deer mortality were strongly correlated with deer browsing rates of the red oak seedlings. In fact, Blossey notes that the relationship is so strong it looks fake (R2 of 0.96). Even with low browsing rates of red oak seedlings, trilium species are still under high browsing pressure. Future research will look into additional plants to use as sentinel species.
Curtis summarized some key recommendations for other communities looking to reduce deer impacts: 1) Develop assessments so the effectiveness of management approaches can be validated; 2) Avoid non-lethal methods, as they have shown little promise in areas where deer can move freely; 3) Develop local expertise on deer management; 4) Community support for the program will be essential; and 5) Once started, some form of deer management will need to be maintained for the foreseeable future.
As Blossey and Curtis note: Deer are a human-caused problem, and we need to fix it!
Featured image “Deer Crossing” by HorsePunchKid is licensed under CC BY-NC-SA 2.0 .
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