There’s a war going on in the forests of the Hudson Valley. On the front lines are Eli Arnow and Avalon Bunge, members of Partners for Climate Action, defending against an onslaught of sapling-munching white-tailed deer. Their tools: building exclosures, ethical hunting, and perhaps their most important weapon: education.
According to the Nature Conservancy, forests in Columbia and Dutchess counties — and across New York state — are not regenerating healthily. The problem is not in the limbs and branches of the trees themselves, but in the forest understory, where, in a healthy forest, seedlings, saplings, wildflowers, and diverse vegetation should flourish. However, hungry deer — whose population has exploded since 1900 — are mowing down the next generation of trees.
On March 29, Arnow and Bunge led a group of roughly 20 Hudson Valley residents into a Gallatin forest. They circled around a knee-high wire fence. Inside was a single trillium, soon to blossom into its distinctive white petals. “50 years ago, I bet this was a carpet of trilliums,” said Arnow. “We need to be protecting these species that are deer candy.” Decades ago, a saunter through the forest floor could yield armfuls of trilliums. Now, even a single one is fenced, monitored, and coddled as if it were the last of a dying breed.
The purpose of the event was to teach people how to build deer exclosures, the ramparts in the campaign against the game. The exclosure — a plastic mesh fence, while not the most visually appealing structure — is put up around areas of forest with intact native biodiversity, protecting the plants from grazing deer. It serves as a nonlethal alternative to hunting.
Attendees, many with their own parcels of land in New Paltz, Woodstock, Stoneridge, Ghent, and beyond, came to learn how to build the exclosures, wanting to do their part to protect what forest they can. Marietta Brill, who owns six acres in Woodstock was present at the workshop, and has seen the forest on her property in peril. “I’ve observed the understory disappearing,” she told the Herald. Building deer exclosures is a tool that she hopes to add to her arsenal. “It’s one of those radical acts that you can do to actually take action and resolve the obvious things that are happening.”
By drilling hooks into the trees, running a wire between them, and hanging the mesh fence off the wire, the squadron of helpers erected about 300 feet of fence roughly seven feet tall. The fence is a low-disturbance tactic in deer deterrence, and has minimal effects on other wildlife, who are able to tunnel underneath or clamber over it.
For Arnow and Bunge, who are also avid hunters, it’s not a personal vendetta against the animals, but an unfortunate yet science-backed reality that the deer are the main stresser behind the regeneration crisis. “We love deer. They’re beautiful, charismatic, and an essential part of a healthy ecosystem,” said Arnow during a webinar in which he spoke about deer overabundance, “but all is not well.”
A 2023 study by the Ecological Society of America monitored seedling and sapling density across 39 national park forests from Virginia to Maine. Of the 39 forests, 27 of them were classified as experiencing imminent or probable failure due to lack of regeneration. The research concluded that “deer browse impact was consistently the strongest predictor of regeneration abundance.”
Compounding the problem, after deer lay waste to the native plants, a gap is created for invasive species. Bernd Blossey, the director of the Ecology and Management of Invasive Plants Program at Cornell University, described this trophic cascade caused by deer appetites. “The deer prefer to eat a lot of the native species, but not necessarily the non-native ones,” he said. “By decimating native species, you take their competitive effect out, and non-native species settle in.” This in turn makes it harder for young trees to gain a foothold against the opportunistic invasives.
Arnow bent down and directed participants gaze towards a small native spicebush in the clearing. “This should be as big if not bigger than that barberry, but the deer hammer it year after year.” Amidst this vying for supremacy between native and invasive plant species, no trees had grown in the clearing for 15 years. “There’s no future for our forests if trees can’t regenerate within these openings,” said Arnow.
Troy Weldy, the director of the Columbia Land Conservancy, has found that the ideal vision of a healthy looking forest has all but faded from our collective memory. “[People will] see a forest that has no understory and look at it and say ‘that’s beautiful,’” he said. For Weldy, a busy forest is a healthy forest. “As an ecologist, what we want to see is thick forests, forests that are hard to see through, forests that are messy.” And it’s what the other wildlife wants, too.
Bunge, who works primarily in endangered pollinators, gave insight into the domino effect that out of control deer populations have on the broader environment. “The plants that the deer are targeting are also the plants that the endangered pollinators rely on,” she said.
The group lingered in a section of forest soon to be fenced in. This part of the forest was cratered and bumpy, hard to navigate, and markedly different from the rest of the leafy forest floor. They were standing in a section of ancient forest. “This hasn’t been disturbed since the glaciers receded,” said Arnow, noting the pit-and-mound topography. Using historic aerial photography and LiDAR, The Hawthorne Valley Farmscape Ecology Program discovered over 5,000 acres of potentially ancient forest in Gallatin. Ancient forests are lands that have never been cleared for agriculture, are untilled, and contain rare soils and diverse ecological communities. These forests, which call for special protections, are not spared in the deer browse. “During some of our spring wildflower surveys, it just really seemed like overall the abundance of spring wildflowers was pretty low,” said Josie Laing, a Botany Technician at Hawthorne Valley. “We suspect that that was as a result of deer.”
There are forces opposed to the deer management work of organizations like Partners for Climate Action, creating some unlikely alliances. For example, both recreational hunters and animal protection organizations are in favor of a high deer population, albeit for varying reasons. Still, whether it’s the DEC or PETA, Blossey claims that organizations are not representative of the voice of the majority of the population.
In a recent paper published in Scientific Reports, Blossey found that more than 70% of surveyed New York state residents were in favor of using lethal means to control deer population, if that meant improvement in the regeneration of forests, as well as other benefits such as curbing Lyme disease. More than that, Blossey said that even self-described animal protectionists are sympathetic to the cause. “When we ask people, do you identify as an animal protectionist? a lot of people say yes,” said Blossey. “But even those people will agree that if you do it for ecological reasons or human health reasons, they will accept to shoot more deer.”
Laura Stark, a biologist at Hawthorne Valley working on the ancient forest mapping, was a vegetarian for over 10 years, but has since taken up hunting after learning about the ecological threats posed by deer. “Over time, the ecologist in me outweighed the vegan in me,” she said.
There isn’t a catch-all solution to the deer problem. Furthermore, the fences are expensive (Bunge calculated the cost to be roughly $700 per acre), and local laws in residential areas make hunting infeasible for many.
To the untrained eye, driving by a lush forest on a summer’s day would never give the impression that it’s in peril. Arnow calls this “the big green illusion.” But advocates like Arnow, Bunge, Weldy, Bossey, Laing, and Stark, urge us to consider the untold story: the understory, lest we see quite literally see the forest for the trees, and that, as Bossey puts it “to look into the future, you don’t look up into the tree canopy, you look down.”