Nellie Hill Tract, Lower Hudson Valley

First Tract in a New Wildlife Refuge

In early 2018, genetic analysis of rabbit fecal pellets – those familiar round droppings found on winter’s snow, collected in plastic vials by biologists and sent to a university lab for testing – confirmed the presence of New England cottontails on the Nellie Hill Tract of the new federal Great Thicket National Wildlife Refuge.

Biologists at Nellie Hill Tract

Biologists Paul Novak, George Molnar, and Mike Horne (l-r) plan improvements to rabbit habitat on Nellie Hill Tract./C. Fergus

Nellie Hill’s 144 acres lie south of Dover Plains in New York’s Lower Hudson Valley. Formerly a farm, the hilly tract is now a mix of grass fields, shrublands, and middle-aged forest.

The Nature Conservancy purchased Nellie Hill, then deeded the tract to the U.S. Fish and Wildlife Service in 2017 as the first parcel for the Great Thicket National Wildlife Refuge, whose purpose is to help wildlife that need young forest and shrubland, including the New England cottontail. Conservationists hope the refuge will someday include holdings throughout the cottontail’s six-state range – which, in addition to New York east of the Hudson River, takes in parts of Connecticut, Massachusetts, Rhode Island, New Hampshire, and Maine.

Biologists knew that New England cottontails lived near Nellie Hill but had not found evidence that these native rabbits inhabited the tract itself. Nevertheless, they continued to run pellet surveys there, detecting only eastern cottontails, similar in appearance to New England cottontails but not native to the region. Now, finding fresh evidence that New England cottontails also occupy Nellie Hill gives greater impetus to making the tract into even better habitat for this rare rabbit.

Mike Horne, a refuge manager with the Fish and Wildlife Service, is in charge of the Great Thicket Refuge. “We’re in the early stages of developing a management plan for Nellie Hill,” he said.

On a day in October 2018, Horne and Service biologist George Molnar joined Paul Novak, a biologist with the New York State Department of Environmental Conservation, to look at habitat on the tract.

“As old farms like this were abandoned,” Horne said, “they began to fill in with shrubs and then trees. They were nice and dense for a few years and offered excellent food and cover to animals like American woodcock, ruffed grouse, towhees, and New England cottontails. But over time, as the trees grew taller and broader, they started shading out the lower vegetation. Gradually the amount of dense, low-level habitat – wildflowers, shrubs, and young trees – dwindled.” That dense, low habitat is exactly what New England cottontails need.

Novak was director of science and stewardship with The Nature Conservancy in the 1990s when TNC acquired the property from a family named Benson. He reminisced: “You could say that the first step in managing this property for wildlife took place back in 1990 and 1991, when TNC chose not to continue grazing the farm’s pastures.”

Tiered Management Plan

Now, Horne and Molnar have begun developing a “tiered management plan” for the site. First, they planted seeds of native blackberry, wild grape, pasture rose, eastern redbud, arrowwood, and chokecherry (all good food or cover plants) on a 1-acre grassy area. They plan to monitor the plantings to determine which species do best in the local soil. Volunteers continue to build brush piles: heaps of cut limbs and branches that cottontails and other wildlife can use to avoid predators and find shelter in cold or stormy weather.

Brush pile built for New England cottontails

Landowners and habitat managers can build brush piles that cottontails use to avoid predators and take shelter in cold weather./R. Martin

“We plan to remove selected trees and open up gaps in the forest,” Horne said. “And we’re looking into more intensive forest management, including possible timber harvests, on the southern part of the tract.”

Timber harvesting, generally done through commercial logging, removes the forest canopy to stimulate thick lower growth. Shrubs and low plants are revitalized. Tree seedlings and saplings shoot up, forming a dense habitat quickly be occupied by cottontails and many other animals.

If timber is harvested on Nellie Hill, a fair amount of tree canopy will probably be left intact. Recent studies in the Hudson Valley by Dr. Amanda Cheeseman, a researcher with the State University of New York, suggests that leaving a higher percentage of trees gives New England cottontails a competitive advantage over the non-native eastern cottontails. Shelterwood and seed-tree harvest techniques are possible approaches, done in stages so that more trees remain in a harvested area over time. Or managers may opt to make small gaps in woodlands by felling a handful of trees growing near one another.

As Horne and Molnar work up a management plan for Nellie Hill, they’re studying Best Management Practices that biologists developed to create the kinds of habitat where New England cottontails will thrive.

At Nellie Hill, Novak, Horne, and Molnar inspected eastern redcedar trees dotting grassy slopes once grazed by livestock. They discussed planting other lower-growing evergreens, such as native juniper, in those sunny settings to provide more winter cover.

They also looked at areas where invasive trees and shrubs such as barberry, buckthorn, bush honeysuckle, and multiflora rose infest the habitat. The first three invasives do not provide good food or cover, but multiflora rose thickets have value in winter, when cottontails hide under the arching, thorn-studded canes and nibble the stems. Efforts to swing the balance of shrubs at Nellie Hill will probably include leaving patches of multiflora rose as refuges for the rabbits.

A 1.4-mile trail system gives hikers, birders, and biologists good routes to use while looking for cottontails and for other kinds of early successional wildlife that should flourish as managers create and refresh young forest and shrublands.

In the future, the U.S. Fish and Wildlife Service will seek to add parcels to the Great Thicket Refuge in 10 focus areas in the six states with New England cottontails. The Service will work with state and private nonprofit partners like The Nature Conservancy to acquire, through conservation easements, donations, and fee purchases, up to 15,000 acres. The process is expected to take decades, since the Service works only with willing sellers, and land purchases land depend on funding availability.

Stuart Gruskin is chief conservation and external affairs officer for The Nature Conservancy. When TNC donated Nellie Hill to the Great Thicket Refuge in 2017, he said of the land transfer: “It had enormous appeal to The Nature Conservancy, because it is in line with our mission of looking for ways of coming up with the most impactful conservation outcomes.” He added, “To be able to kick-start the establishment of this newest national wildlife refuge, and also magnify the impacts of our property, was irresistible.”