Brookline’s Greg Kallfelz, 7, and his brother, Dean, 9, are showing in a special way that they give a hoot – about birds, especially bluebirds.

The boys are members of the 4-H Enrichment Club, a group of 12 people, that meets on the fourth Tuesday of each month at the Lawrence Barn Community Center, at 28 Depot Road in Hollis.

The barn is a refurbished, historic building with a legacy going back to the 1780s during the American Revolution. It is a space well appreciated by neighbors and those who rent the space for various functions.

The Kallfelz brothers are the makers of Birdboy Suet – a pure, homemade treat for wild birds. The product is a nutritious mix of melted, then cooled, beef suet fortified with seeds, fruits and grains. Batches of the dense, white concoction, brightly speckled with corn kernels, apple chips and other variously colored ingredients, are made under parental supervision in the Kallfelz home.

Kathy Kallfelz, the mother of the entrepreneurs, said her boys have been into bird watching for about two years. They have found, she said, a rich experience in their local 4-H activities, endeavors through which the family enjoys the friendship of like-minded nature lovers, 4-H members from several towns.

“The suet-making began so we would have some for our own birds,” Kallfelz said. “We do some baking and kitchen projects for our own enjoyment but the boys liked making the bird suet and were really excited when it started attracting more birds to our yard. Selling the product as a fundraiser came later.”

The boys learned a lot about the region’s birds and animals, local conservation efforts and the importance of making the best of one’s resources at the monthly 4-H meetings and at their home-school classes. The family is a part of the Relaxed Homeschoolers Network, consisting of some 400 families throughout New Hampshire, Kallfelz said.

The boys, who originally called their product, Apple Crumb Suet, would cook up a batch and then send packages of their handiwork to an uncle who lives in Arizona. Whenever he received a supply, he would call and tell them about its impact on his wild birds.

“Those woodpeckers really love that bird-boy suet,” he’d say.

Kallfelz said the name “Birdboy Suet” stuck. Soon, her sons were making labels and selling the product at the Milford Farm Market. The market, from November through May, is held on various Saturdays on the second floor of Milford Town Hall on Union Square.

Upcoming market is from 9 a.m.-noon Saturday, March 3, Other dates are listed online at MilfordFarmersMarket.com. The boys have seen a surge in sales. They expect to bring with them a generous supply of Birdboy Suet, priced at $5 per cello-wrapped square.

Few can resist the sales pitch of the two young men. The brothers sit alongside a table upon which is displayed posters about 4-H activities benefited by the suet sales. Photos of a 4-H bluebird project are prominent. Last winter, the boys built numerous wooden bluebird houses and erected them on wooden poles.

They monitored the sites and counted the bluebirds who took up residence there. They watched for harmful insects such as the blowfly, an insect whose larvae that can become a parasite on birds. They checked for two-winged squatters – house sparrows and house wrens – that tend to move into a bluebird house and make it their own. The effort won for the boys a 4-H blue ribbon, for the project entailed keeping charts and graphs and notations as to the weather, pests, numbers of nesting couples and the health of the birds.

Greg and Dean displayed their blue ribbon at the most recent farm market. It is usually kept at home in a place of honor, not far from the hutch housing their pet rabbit and the coops that shelter their two, pet pigeons.

The boys’ dad, John, a civil engineer for the state of New Hampshire, is the one the brothers delegate to go shopping for bluebird-house materials and hardware with money from the proceeds of selling Birdboy Suet.

“It was really neat to see the boys earn some money and give it to their dad, so he could go and buy all the hardware and supplies,” Kathy Kallfelz said. “The bluebird project has taught them some valuable lessons, everything from kitchen skills to planning and budgeting and building.”

Those lessons also include learning how to educate people about birds.

“I like the selling part of it,” Dean said.

“I also like telling people bird facts. When a person comes up to me to buy some suet, I tell them about birds they never even heard of. Did you know swallows can have flocks made up of thousands of birds?”

The boys also learn how to satisfy their customers.

“When a satisfied customer comes up, I’m pretty glad about it,” said Greg. “It’s a lot of hard work making the suet but it’s worth the effort. Sooner or later, people have to buy new suet.”

The boys’ fame is spreading. Residents from Milford, Hollis, Merrimack, and other towns now seek them out at the local farm markets.

Merrimack resident John Lastowka, chairman of the Merrimack Agriculture Commission and the chairman of the UNH Cooperative Extension Service of Hillsborough County, is among those crediting the enterprising spirit of the brothers and their contributions to the programs offered through 4-H.

The 4-H clubs throughout the state are the educational programs of the UNH Cooperative Extension Service, said Lastowka. The name refers to Head, Heart, Hands and Health, all of which are pledged by members to the betterment of their club, their country and their world.

Lastowka, a businessman and owner of Lastowka’s Maple Gate Farm, a 40-acre spread of fruit trees, grape arbors and blueberry patches overlooked by more than 30 bluebird houses, said all birds provide a valuable service not often recognized – they eat bugs and thereby help all kinds of crops thrive.

“These young men, Greg and Dean, and their fellow 4-H members – people who promote in so many ways the agricultural efforts going on in New Hampshire – are to be commended,” Lastowka said. “Projects such as the bluebird study supported by Birdboy Suet sales teach so many valuable skills. The brothers have learned organizational skills, public speaking and how to handle money. It’s such a good thing.”

The Milford Farm Market thus far is the boys’ favorite destination for suet selling.

Soon, however, winter will be done and crowds will be heading to Merrimack’s Farm Market, held weekly during the summer at The Commons shopping center, an easy-to-access location on Daniel Webster Highway, opposite the Merrimack Post Office. There, selections range from fresh produce and fruits to artisan-baked breads, grass-fed beef and fresh seafood.

Numerous towns throughout New Hampshire boast farm markets that bring the best of locally grown wonders to consumers who want to support local agriculture and at the same time acquire the freshest of goods. Most markets have grapes and greens and baked goods. They have jams and jellies and honey. But not so many have Bird Boys Suet.

For more information about the 4-H Enrichment Club in Hollis or about Birdboy Suet, e-mail kkallfelz@aol.com.