“The phoebe is building a nest again under the canoe,” said Gudrun Keszocze, naturalist of Hirundo Wildlife Refuge, shaking her head.

She sat at a long table in the Parker Reed Shelter, a cozy, red building on the shores of a man-made lake christened Lac D’Or (Lake of Gold) by its creator, Oliver Larouche, Hirundo’s founder.

A space heater warmed Keszocze’s back as she looked out a wall of windows to the calm surface of the lake, disturbed only by a trio of swiftly moving wood ducks.

“The swallows are just back this week,” observed Ray “Bucky” Owen, who sat in the corner. A former chairman of the University of Maine Wildlife Department, Owen is on the preserve’s board of trustees.

Hirundo Wildlife Refuge, a 2,402-acre preserve in Old Town and Alton, includes parts of Dead and Pushaw streams and a diversity of hardwood and evergreen forests. A significant part of the preserve covers a piece of the 6,000-acre Caribou Bog Wetland Complex, one of the largest wetland systems in Maine.

Founded by Larouche in 1965, the preserve has expanded from his family’s 3-acre camp lot to more than 2,400 acres. And in 1982, it was entrusted to the University of Maine.

Today, a clearly marked trail system allows visitors to wander 300 of those acres.

“It was an unknown gem,” said Owen. “It’s still pretty much unknown, but getting better all the time.”

“Hirundo” is the Latin word for swallow, a bird that flocks to the preserve each spring to nest in scores of red nesting boxes that have been erected on the land, shelters that the occasional bluebird, squirrel or mouse family will take advantage of as well.

From cleaning out the boxes each spring, with the aid of UMaine’s Gamma Sigma Sigma sorority, Keszocze has learned that swallows tend to make their nests of grass and duck feathers, where bluebirds use pine needles. Wasps like the boxes, too.

That morning, the Hirundo naturalist walked along the trails (as she so often does) to note the changes. Early April ushers in budding maple trees, bright yellow coltsfoot and sunning painted turtles.

“I keep tabs on everything,” she said, from muskrat pups on Pushaw Stream to the hemlock porcupine haunts.

In the past three years, the reserve has undergone some big changes, and Keszocze, Hirundo’s first full-time naturalist, has been an integral part of that transformation, as has the preserve’s caretaker, Fred Bryant.

The board of trustees, which first was composed of the Larouche family, has rapidly expanded to include university professors, natural ecology educators and archeologists. And through trail revitalization and educational programming, they’re making the land and waterways more accessible to the public.

From Lac D’Or, Keszocze treads softly over flattened field grasses along the Wabanaki Trail (0.4 mile), which leads through wetlands and traces the shore of Pushaw Stream to a stand of pines that has been placed on the National Register of Historic Places. The needle-coated ground is the site of a Red Paint Indian fishing village circa 5000 B.C. Excavated in 1972, the artifacts are now displayed at the Hudson Museum in Orono.

The Wabanaki Trail is one of two interpretive foot trails recently created by UMaine students — both guided by brochures available at trailheads and online.

In addition to the new trails, visitors have quickly embraced the many new outdoor programs Keszocze has scheduled in the past year. Last spring’s mushroom walk attracted 80 people, and the winter ecology program taught by Owen brought out 50. Full moon paddles and owl watches also have proved popular.

“Sometimes when we’re on the water we see nighthawks, mink, otter and beaver,” said Keszocze, who also leads more personal group nature walks and canoe trips upon request. “Last summer, we saw an otter with three young popping out of the water.”

Originally from Aschaffenburg, Germany, Keszocze came to the U.S. in 1980. Beginning on the west coast, she made her way across the country to Maine, where she became a registered guide. Her background as a naturalist comes from her own extensive experience outdoors — guiding ocean canoeing and kayaking trips — and her studies at UMaine, where she earned a degree in botany and taught German.

Throughout April and May, she has scheduled Hirundo workshops on bird watching, apple tree-pruning, medicinal edible plants and invasive plants. And for those who would like to help Hirundo’s work force of two prepare the trails for the summer, Trail Day is scheduled for 9 a.m.-3 p.m. Saturday, April 28. Just bring a lunch and sharp tools, and call to register.

From Wabanaki Trail, Keszocze slogged through the damp terrain in her rubber boots to visit a beaver dam on Pushaw Stream. On the bank, freshly gnawed branches signified that someone was home, most likely inside the lodge sleeping. A mallard floated lazily downstream as Keszocze used a stick to sift through otter skat reduced to a pile of silvery scales and fish teeth.

Tracing old beaver paths through red osier dogwood, Keszocze flushed out a woodcock before emerging onto Thornplum Trail (0.3 mile), which is walled with dense, unforgiving hawthorn bushes.

“Last summer, we had a black bear with three cubs,” she said. “It looks like they might be around this year, too.”

While pointing out deer beds and turkey scat, a grouse lighted from one of the preserve’s ancient apple trees. Though she barely spotted the bird, she knew it by the heavy sound of its wings.

Stopping at a pine, Keszocze pointed out a fresh, rectangular hole made by a pileated woodpecker, and beneath, tiny holes drilled by a yellow-bellied sapsucker. Later in the spring, migrating hummingbirds would also feed from these holes, explained Keszocze. “In nature, nothing happens in a vacuum.”

She pauses to watch a group of swallows diving and dancing over the meadow before making her way back to Parker Reed Shelter on Lac D’Or — home base.

“We’ve made a major effort with the schools,” she said, picking up a few fresh water clam shells left on the pond’s bank by snacking minks. Last spring, fifth graders collected such middens for research. The preserve plans to use the shells to gauge mercury content in the water. Along with UMaine students and professors, the fifth-graders also surveyed trees at the preserve. These projects will continue in the fall.

To offer more outdoor programs to the public, Hirundo has been reaching out to the Sunkhaze Meadows National Wildlife Refuge in Milford, the Orono Land Trust, local schools and organizations.

“In the end, we all want the same thing,” Keszocze said, “for people to understand and care for the natural world.”

For information, visit www.hirundomaine.org; visit lacdor.blogspot.com; call Bryant at 827-2230; or call Keszocze at 944-9259.

Aislinn Sarnacki is a Maine outdoors writer and the author of three Maine hiking guidebooks including “Family Friendly Hikes in Maine.” Find her on Twitter and Facebook @1minhikegirl. You can also...