THE FOREST CLASSROOM

Left: NHFG biologist Brett Ferry uses a small plastic vial to collect a cottontail pellet for laboratory DNA analysis. Right: In October 2021, UNH students worked to improve New England cottontail habitat at the Forest Society’s Hills Family Forest in Durham.

Searching for Bunnies in the Brush

By Carrie Deegan

The habitat of the New England cottontail is not a pleasant place to go for a walk. Our native cottontail, also known as a “brush rabbit,” prefers an environment with upwards of 20,000 small woody stems per acre—in other words, an impenetrable thicket. I came to this realization the hard way this winter at the Forest Society’s Hills Family Forest in Durham as I looked for evidence of bunnies with Brett Ferry, a biologist with the New Hampshire Fish and Game Department (NHFG).

“We’re looking for tracks and poop,” Ferry explains, as we slowly pick our way through thorny shrubs looking for signs on the week-old snow. The pelleted excrement of cottontails is circular compared to more elongated deer scat, but it can be roughly the same size. “I usually tell people they look like M&Ms,” Ferry chuckles. “Well, the brown ones anyway.” I concentrate on this search image as I squeeze between saplings, my jacket snagging on raspberry canes and sending tufts of down airborne.

Collecting rabbit pellets is the most efficient way biologists have found to monitor populations of the New England cottontail, which has suffered a range reduction of more than 80 percent since the 1960s. In New Hampshire, where only two small populations remain—one in the Seacoast and a second in the Merrimack River Valley—the species is listed as endangered. To monitor cottontail populations, scat is scooped into small vials during transect surveys and sent off to a lab at the University of New Hampshire (UNH) where researchers analyze the DNA to decipher how many individual animals live in a habitat patch, as well as their parentage (who is related to whom and how).

The southeastern corner of the Hills Family Forest and the adjacent Bunker Creek property, owned by NHFG, in Durham contain about 15 acres of highquality habitat, but during our visit we didn’t find any cottontail pellets. This scrubby “young forest” hasn’t developed on its own but was created by deliberately clearcutting a more mature forest and planting shrubs about ten years ago. Once it grew up into a thick tangle of alder and poplar saplings, New England cottontails were released here in two consecutive years as part of a captive breeding program to augment struggling wild populations in the region. Unfortunately, these releases were unsuccessful, and the rabbits did not survive to reproduce. “It was disappointing after having releases be successful at other locations” Ferry says.

At the nearby Bellamy Wildlife Management Area (WMA), where management efforts have created about 100 acres of suitable habitat, released cottontails have done much better, reproducing in the wild and maintaining their small population after an initial release of eight rabbits in 2013. In 2018, a pellet from one of the Bellamy WMA rabbits was collected on the Hills Family Forest property, igniting hopes that expansion across these landscapes might be occurring, but since that time pellet surveys at the reservation have come up empty.

In the meantime, the habitat created for New England cottontails needs maintenance to remain prime, whether it is currently occupied or not. Students from two UNH wildlife classes spent two days in October 2021 cutting larger stems on the Hills Family Forest habitat, hoping to stimulate those trees to sucker with the additional small stems that cottontails require. Cut brush was heaped in large piles to create even more areas of potential cover for the rabbits. It’s a lot of work and a big commitment on the part of landowners, who will ideally work cooperatively to manage habitat patches on a rotational basis ensuring there is always some prime cover and foraging territory available.

The New England Cottontail Project, which was initiated in 2009 and involves more than 50 partners, including the USDA’s Natural Resource Conservation Service (NRCS), U.S. Fish & Wildlife Service (USFWS), state wildlife agencies, land trusts, universities, and municipalities, has worked with landowners to create and maintain more than 1,000 acres of “early successional” young forest habitat in the state. Many of these habitat projects have been at least partially funded through programs like State Wildlife Grants, the National Fish and Wildlife Foundation, NRCS’s Working Lands for Wildlife Program or New Hampshire’s “Moose Plate” Conservation License Plate grants.

Nearly a dozen years into the recovery program, Brett Ferry says the prognosis for New Hampshire’s native cottontail is both encouraging and disheartening. Rabbits in the Seacoast region have been responding well to management actions, but the Merrimack River Valley population, which is centered in Londonderry and had been larger than the Seacoast population, has been struggling. A decade of rapid development has fragmented the landscape there and considerably hampered movement of New England cottontails. At the same time, non-native Eastern cottontails, released in southern New England to augment hunting stock in the early 1900s, have expanded northward into the Londonderry area in the past several years. The slightly larger Eastern cottontails are more generalist in their habitat needs and have a wider field of peripheral vision, allowing them to escape predators and outcompete the native brush rabbits. Helped along by milder winters, which increase survival and lengthen the breeding season, Eastern cottontails have begun to expand and displace the New England cottontails in the Merrimack River Valley. “The Eastern cottontails hit like a wave,” Ferry says. “Now the Merrimack population of New England cottontails is less than half of what it used to be.”

Considering recent setbacks and successes, NHFG biologists remain hopeful that New England cottontail populations will grow and stabilize in the state. “It’s an uphill battle, but all we can do is try,” Ferry declares. Although maintaining suitable, contiguous habitat will be an ongoing challenge, Ferry is positive that the effort is worth it. “What is happening to the New England cottontail is really an indication that something is out of balance,” he says, “which means other species are struggling as well.”

It is true that other animals that depend on early successional habitat, such as woodcock, grouse, blue-winged and golden-winged warblers, wood turtle, and black racer snakes, have also experienced marked population declines. “We’re creating and maintaining all of this habitat for cottontails, but it’s benefiting every other species that uses this type of habitat, from mammals to songbirds and all the way down to native pollinators,” Ferry notes. In other words, impenetrable thickets are good for more than just brush rabbits even if they don’t make for pleasant human outings.

New England cottontail (inset) populations have decreased drastically over the past 50 years primarily due to a lack of suitable shrub habitat (above) as forests have matured and development has fragmented New England’s landscape.

Carrie Deegan is the community engagement and volunteers director for the Forest Society.

A carpet of white pine seedlings flourish at the Diehl Family Forest in Lempster, N.H., after a harvest in 2017 made way for a new generation of trees to grow.

Oh, You’re a Forester…Do You Plant Trees?

By James Frohn

As a forester, a common question I get is “do you plant trees after logging?” While this is common practice in other parts of the country and the world, here in New England tree planting as a part of forestry is unusual. Instead of planting, we typically rely on natural regeneration of trees. There are several reasons for this.

Why Utilize Natural Regeneration

Due to adequate year-round rainfall and reasonably fertile soils, trees readily regenerate on their own in our region. Consider that at one time much of New England was cleared of its forests and converted to agriculture, then forests readily grew back on their own after farm abandonment, with limited planting by people.

Because trees regenerate well on their own, planted trees have lots of competition. Controlling this competition is costly and time consuming. (I managed a property where a stand had been cleared of hardwoods and planted with spruce twenty years prior. It was hard to tell it had been planted due to the dense growth of sugar maple and yellow birch. The spruces, which represented a substantial investment of money, time, and labor, were shaded out by the hardwood growth.) In our region, most species that regenerate naturally have commercial value. Therefore, planting to ensure a steady supply of favorable species is not as necessary as in other areas of the world where only a few species have marketable value.

Growth rates are another factor, as it takes a long time to grow a tree to sawlog size in New England. Usually, the cost of waiting for trees to grow outweighs the investment to plant the trees. In other regions with shorter time spans from seedling to harvestable tree, it makes economic sense to plant.

KEEPING FORESTS AS FORESTS

The Forest Society proudly practices sustainable forestry on our lands, with the goals of enhancing the diversity of our forests, producing renewable forest products, earning income to support our mission, and safeguarding soils, water, and unique features. Our foresters use silviculture when implementing harvests that allow for natural regeneration to take place.

To learn more about how and why the Forest Society practices sustainable forestry on our lands, visit forestsociety.org/cutting-trees-conservation. To read about our active and recent timber harvests, visit forestsociety.org/forest-society-timber-harvests.

While most of our tree species have commercial value, some species are worth more than others in the market. Similarly, some species benefit wildlife more than others, or are more adapted to a changing climate. The task for foresters is to create conditions for the natural regeneration of desired species, whatever the goal might be. This is where silviculture comes in.

Silviculture

Silviculture, according to silviculturist David M. Smith, author of a widely used text on the subject, can be defined as “the theory and practice of controlling forest establishment, composition, structure, and growth.” Foundational to silviculture is silvics, “which deals with the principles underlying the growth and development of single trees and of the forest as a biological unit” (Smith).

Sunlight and Shade

One of the most important concepts in silvics is shade tolerance. Tree species fall on a spectrum of shade tolerance, from very shade tolerant to very shade intolerant, and different gradients in between. A tree species’ shade tolerance characteristics are critical when considering how to get new seedlings established.

Very shade-tolerant species include hemlock, red spruce, and beech. These species can germinate and persist in the deep shade of a closed canopy forest. They don’t necessarily thrive in these conditions, but they will persist, which gives them a competitive advantage over less shade-tolerant species. A sapling size hemlock may be mistaken for a young tree, but, it may be 40 or 50 years old or more.

On the other end of the shade-tolerance spectrum, we find species such as paper birch and aspen. These species won’t regenerate in shade. They need full sun and warm soil to germinate and thrive. Known as pioneer species, their competitive advantage is that they are among the first trees to establish after a heavy disturbance such as fire or clearcutting.

Between these two extremes lie numerous species: red oak, white ash, yellow birch, and white pine all exhibit intermediate shade tolerance. They tend toward one end or the other of the spectrum; for example, yellow birch is less tolerant while white ash is more tolerant of shade.

Site Plays a Role

Site is also a factor in silviculture. Soil fertility and structure, drainage, slope, aspect, and elevation all play a role in which species of trees can be regenerated on a site. Site characteristics need to be taken into consideration in forestry planning, but there is little, if anything, the forester can do to influence them. The forester can, however, manipulate the light levels that reach the forest floor. This is done through different silvicultural treatments, which involve cutting trees and often include selling the harvested wood.

Based on stewardship goals, site characteristics, and shade tolerance of the desired species, foresters develop various silvicultural treatments. They range from clearcutting to regenerate shade intolerant species to single tree selection to regenerate very shade tolerant species, and many variations in between.

Planting Can Play a Role

Efforts at natural regeneration aren’t always successful. Excessive deer and moose browsing can keep natural regeneration from developing, and invasive plants can prevent successful establishment of native tree species. Poor logging practices that haven’t taken the future forest into consideration can hinder regeneration of desired species. For example, the stand may have had spruce and fir seedlings that became established in the shade, but skid trails weren’t planned to avoid damage to the seedlings, resulting in their loss. Along with this, misunderstanding the silvics of the target species can result in regeneration failure. (Clearcutting in spruce-fir when no seedlings were established prior to harvest will result in shade intolerant hardwoods occupying the site, rather than the desired spruce and fir.)

In these situations, enrichment planting is an option to enhance the regeneration. The goal is to enrich the species composition, improve timber value, or increase stocking. The focus isn’t on establishing plantations of trees, but rather to fill in places where regeneration may have failed or where species composition lacks diversity. (I worked on a planting project in Maine where the understory prior to harvesting was almost entirely beech. The goal was to improve the species composition and future value by planting spruce and pine with the existing hardwoods.)

Planting can also enhance wildlife food sources. Native dogwoods, elderberry, and winterberry, or introduced, but non-invasive, species such as apple all benefit wildlife. Like all plantings, these shrubs and trees need to be protected from competition and wildlife damage while they become established. Before deciding to plant, examination of the site is important. See if fruit and nut-bearing plants are already there and can be helped along by cutting trees that are shading them out.

Most of us like the idea of planting trees. In a forested setting, however, planting is often not needed at all. But, planting can play a role, when regeneration is unsuccessful, or species diversity needs to be enhanced.

James Frohn is a forestry field specialist and an instructor field specialist for the University of New Hampshire’s Cooperative Extension.

Learn More:

If you want to learn more about stewardship of your forest, contact your county forester to set up a site visit. If you’re looking to plant trees or shrubs, the New Hampshire State Forest Nursery is a good source to purchase seedlings. Visit nh.gov/nhnursery for more information.