SHARON — When maple sugaring time rolls around at Moose Hill Wildlife Sanctuary, they do it the old-fashioned way.
In the last six weeks of winter, as the contrast between daytime and nighttime temperatures causes tree sap to rise from the roots to the branches, Mass Audubon staff and local volunteers collect sap by hand from taps driven into more than 100 sugar maple trees. They transport hundreds of gallons of sap — a tractor with a large plastic tank helps a lot — to the traditional “sugar shack” and boil the sap down on a wood-fired evaporator. It takes about 40 gallons of sap to yield 1 gallon of syrup. Then they filter, bottle, share, and sell it.
The sweet result, the last significant commercial product to be collected on land in the wild, will be shared at Sunday’s Maple Sugaring Festival from 11 a.m. to 3 p.m. and next weekend on both Saturday and Sunday. The festival includes a tour of the sugar bush and a demonstration of the sugaring process in the sugar shack.
Native American and Colonial characters will re-enact the sugaring process and discuss other daily chores. Everyone gets to taste some freshly made syrup.
Sugaring is a New England end-of-winter agricultural practice dating back to Colonial times and to Native Americans before them, long serving as a supplementary income producer for family farms. More recently, commercial maple syrup operations have produced more than three million gallons of syrup annually; Massachusetts produced 63,000 gallons of maple syrup last year, bringing in more than $3 million to the state’s 300-plus maple producers.
At Moose Hill, however, the practice is as much about education as commerce, said sanctuary director Christine Turnbull.
“It’s so concrete,” Turnbull said last week as she led a visitor over a snow-packed footpath through the woods.
“It’s not just concepts,” she said. “And it’s a unique New England thing.”
The 2,000-acre Mass Audubon wildlife sanctuary practices that New England thing in the traditional way. As sanctuary staff and volunteers led 50 first-graders on a tour of the “sugar bush” where sugar maple trees are tapped and the shack where the sap is boiled and processed, staff member Vin Zollo demonstrated tapping a tree. He used a hand drill to make an incision on an 80-foot roadside sugar maple, then inserted a metal spout and tapped it in with a hammer solidly enough to hang a metal bucket on it.
The bucket comes with a cover to protect the sap. Some trees can take two and even three spouts, Zollo said. But you need to make new taps every year.
“The spout holes start to heal and pop out the spout,” Zollo said. “If you see last year’s hole not healed up, it’s a sign of lost vigor.”
You drill the new hole far enough away from the closed one so as not to harm the tree.
At Moose Hill, most of the sap comes from the 100-tree sugar bush located in an old farm holding that is now part of the sanctuary. A secondary site includes some 30 trees. Colonial farmers planted two “marriage” sugar maple trees outside their house, Turnbull said, and those trees would produce a stand of maples.
Zollo uses the tractor to collect the sap from the pails — in place of the earlier yoke with hooks for two pails — and take it to the sugar shack. The shack, a roofed shed with open sides, contains the sap-boiling evaporator, several holding tanks for sap, a long firebox underneath the evaporator, about three cords of neatly chopped and stacked firewood — and, last Tuesday, three volunteers sporting Moose Hill caps.
The volunteers keep the wood fire glowing. “We do it the old-fashioned way,” said volunteer Jack Hazen of Sharon. “This is the warmest place to be when you’re sugaring.”
The firewood is culled from storm damage to the property’s trees. “It’s one factor we don’t have to worry about,” Zollo said.
The evaporator causes the sap to flow through a series of channels as it grows hotter and hotter. The volunteers boil it up to 219 degrees and use a hydrometer to measure the density; 66 percent sap is the recognized standard for syrup. Then they bottle it, sell it, and share it with festival visitors.
Last week Moose Hill staff and volunteers taught science and history in the classroom of the great outdoors to elementary school students from Pine Hill School in Sherborn and Placentino Elementary School in Holliston. The “teaching naturalists” divvied up the groups and conducted tours of the sugaring operation while mixing some folk history with the science.
According to volunteer Tracey Costa, a Native American legend explains how people learned to find a “natural ambrosia” in the trunks of maple trees. A Native American hunter named Woksis put his ax into a tree before going hunting. After its removal, his wife, Cleta, noticed water dripping out of the cut, collected the water to use in cooking, and noticed a sweeter taste in her food. She began cooking all the family’s food in sap to sweeten it. Humankind has been reaching for the syrup when faced with a stack of pancakes ever since.
Costa said the Moose Hill Wildlife Sanctuary also displays some of the hand tools used by early farmers, including a wooden yoke for carrying pails of sap. In Colonial times children were happy if they “got a yoke for Christmas,” which made hauling gallons of sap a little easier.
Sanctuary staff said the long cold spell has made for a slow start to the sugaring season this year. Ideal conditions require the combination of below-freezing temperatures at night and above-freezing temps during the day to stimulate the trees to send plant nutrients upwards for new growth.
The Maple Sugaring Festival, at 293 Moose Hill St., Sharon, will satisfy appetites indoors in the sanctuary’s Nature Center building by offerings of maple-flavored “delectables” including pancakes with maple syrup, “sap dogs” (hotdogs boiled in sap) on buns, and maple sugar flavored popcorn.
Guided walking tours leave every 15 minutes from 11 a.m. to 3 p.m. The event costs $8; $7 if you reserve in advance; and free for children under 3. You can reserve for next week’s dates at massaudubon.org or by calling 781-784-5691.