Deer

Ecosystems Protection

The Irvington Woods park, containing 260 acres of native woodlands, a rare swamp, large wetlands and 50 acres of precious old-growth forest. The Old-Growth Forest Network recently recognized the Irvington Woods as a crucial link to larger more remote forests. Residents fought for 40 years to preserve it and now it is a thriving community hub for ecosystem stewardship education programs. But in the last 30 years, the Irvington Woods has lost approximately 90% of its understory.

Concerned about the declining state of the Irvington Woods, the Irvington Woods Committee formed an Ecosystems Protection sub-committee to understand the problem. After extensive analysis, it was determined that soil health was not the issue and that deer overpopulation is the cause of a dramatic decline in forest understory, regeneration, seed bank, and many species who depend on the forest for food and habitat


To protect the long-term health of the Irvington Woods Park from the overpopulation of white-tailed deer, the Committee is recommending the establishment of a deer management program. In consultation with experts, agency partners, and Westchester parks that have undertaken similar efforts, we propose hiring a highly qualified professional bowhunter. The goal of the program would be to maintain deer numbers at 20 per square mile to allow for a balanced ecosystem in which regeneration of our native plants and trees is possible for the good of all of the creatures that depend on them. 


Solutions:  The Irvington Woods Committee does not recommend sterilization, birth control, baiting and culling deer, sport hunting or fencing the woods. The committee recommends hiring one highly vetted professional bow hunter to restore the deer population to a harmonious balance with the rest of the species, and to donate the meat to a food bank. Professional bow hunting is safe, efficient and humane. 12 Westchester parks and preserves are successfully practicing Bowhunting, including the County. Some for as long as 15  years. Case studies, like Teatown and Rockefeller demonstrate clear regeneration including increased survivability of Wood Thrush birds


While fencing may be deployed in small areas as a supplementary measure, it is expensive, blocks other animal movements, pushes the deer onto neighbors and roads, and requires heavy maintenance. Fencing one section alone accelerates the demise of the unfenced woods. The cost to fence the entire woods would pay for a professional deer manager for 80 years. Fencing does not address the root of the problem and residential deer fence permits are on the rise - we are in danger of becoming a gated community. 


Contraception: not commercially available in NY State; extremely difficult to implement in roaming population.
Repellent & frightening devices: effectiveness is short lived as animals adapt.

Habitat alteration: removal of vegetation goes against efforts to revitalize Irvington Woods Park.
Capture and relocation: difficult and expensive. Capture and transport causes stress with 25% deer mortality rate. Tranquilizers used pose a health risk to humans if exposed.

Predator introduction, poison, parasite or disease introduction, capture & kill, bait & shoot: unsafe or severe.
No intervention: accept consequences of increased damage to entire ecosystem, increase of car collisions and rates of tick-borne diseases.

Overview of the problem


Assessment of the Woods: drastic lack of regeneration, dwindling seed bank and declining biodiversity. Deer browse is the biggest cause. 


Deer population is 7x what the ecosystem can support: 57 deer where there should be  8, or 141.5 per square mile instead of 20. Population growth = 40% year.


Forest supports food webs and habitat: 100% of ground & shrub nesting birds are in decline. The majority of mid-canopy birds, turtles, small mammals and amphibians are affected too. 


Invasive species exacerbate the problem: As trees come down, light encourages growth and the invasive species that are unpalatable to deer take over. With Beech Leaf Disease killing our 2nd most populous tree over the next five years, the remaining native forest will collapse. 



Future Projections: with no regeneration, 64% less trees by 2050. Declines in carbon sequestration, storm water absorption, air quality, sound barrier, as well biodiversity and habitat. 


Find a one page summary for print out here. 


And a 2 page problems and solutions fact sheet here.


See an Irvington Woods Committee letter to the board here


Find a letter about successful bow hunting deer practiced by the Audubon here which states "Saw Mill River Audubon recognizes that forests in our area are severely stressed from many factors. Among those factors is the absence of healthy forest understory, which is clearly attributable to deer overbrowsing. This is well-documented by peer-reviewed scientific study and easily observable with the lack of understory growth up to the “browse line”" 

“If deer continue to ravage our forests for a generation of canopy trees, the forest itself will cease to exist. The browse that deer depend on will be gone, resulting in mass starvation of any remaining animals.” 

– Douglas Tallamy, Conservationist



We are ubiquitous on most of the landscape and we are already manipulating it for good or ill, whether we know it or not. And I think we have a responsibility, as a keystone species, to manage the ecosystems around us for the good of all of their inhabitants – the plants, the animals and even the people.” 

– Jim Sterba, Conservationist 

Watch the Irvington Woods Ecosystems Protection Committee presentation to the Board of Trustees

See the presentation slides here and the detailed report behind those slides. And a presentation on the Rose Petal theory put together in response to the board's concern that deer will fill the void from neighboring properties. The Board of Trustees is currently considering options

Scroll down for extensive reports on deer impacts.

IWC Ecosystem Protection —Jan. 10th Meeting

Will deer move into the void if we hunt? Studies indicate deer like to stay in a defined home range of 200-400 acres. Learn more here. 

Analysis by Conservationists

"In the Hudson Valley, deer browse currently impacts forest renewal by as much as 25%."

--Charles Canham, of the Cary Institute of Ecoystem Studies


“The entire food web is unraveling,” Bernd Blossey, a professor of natural resources at Cornell University. “I call deer ‘ecological bullies,’” he adds — Bambi, a bully! — “taking house and home and the ability to live away from other organisms, whether they’re birds, other mammals, insects or plants.”


The Nature Conservancy several years ago argued that deer might be “a bigger threat to Eastern forests than climate change.” * And things have only worsened. Doug Tallamy, an entomologist and wildlife ecologist at the University of Delaware, tells me that white-tailed deer in the East are now “about 14 times over the carrying capacity,” meaning the ability of the ecosystem to sustain the species.


Addressing the Impacts of Overabundant Deer and Invasive Plant Species in Northern New Jersey: Strategies for Forest Restoration by Dr. Jay Kelly

Nature Wars by Jim Sterba, Author

Loss of vegetation results in loss of habitat:


Watch how re-introducing wolves to Yellowstone reduced the deer population and dramatically impacted other species. 

Studies on Deer Impacts

 Park (https://www.nps.gov/rocr/ learn/management/white-tailed-deer-management.htm) in the U.S. capitol, and in the small village of Cayuga Heights in central New York (https://cayuga-heights.ny.us/projects-2/deer-management/).

Studies in the Irvington Woods and Nearby Parks


Irivngotn Woods Inventory and Management Plan, created with the DEC 

Soil Health Assessment created with Cornell Waste Management Institute and NYS Department of Transportation

"A well-run deer management program has lowered the deer population by more than half in the Mianus River Gorge, and our data strongly suggests that these efforts are having a positive effect on woody regeneration".

 --Chris Nagy, Ph.D. Director of Research and Education - Mianus River Gorge, Bedford, NY


Rockefeller State Park Preserve: Study showing increased survivability of Wood Thrush birds in areas of deer management:

Rockefeller2019 (1).pdf

History of Deer Management

"Studies suggest that since the last Ice Age, humans probably killed more White-tailed Deer for food, clothing and other uses than all other deer predators combined. In just the last few decades,  for the first time in 11,000 years, [suburban] sprawl man has put huge swaths of the White-tailed deer's historic range off limits to its biggest predator. We have largely taken ourselves out of the working landscape and we've mostly forsaken both the destructive ways and stewardship skills of our ancestors. But the comeback of wildlife all but demands that we reconnect to the natural world that is right out around us, relearn old skills and develop new ways of practicing those skills better." 

-- Conservationist and nature writer Jim Sterba

Wild flowers at the Irvington Reservoir dam in 1905. These could not survive now.