I n mid-April, when winter’s only remainder was the foot-beaten ice in shady sections of trail, I took my first spring walk to the Brunswick Town Commons. Just where they were last year, a few small fists of skunk cabbage had punched through the surface beside the trail by Coffin Pond, and the woods’ winter-quiet had gone over to birdsong.

I had with me a new roll of pink “flagging” tape, and my aim point was a small meadow just south of the 71- acre, central Commons’ border. That meadow is part of the Greater Commons, a 113-acre parcel of town-owned land designated as open space. As the flagging tape suggests, I had a mission beyond the simple pleasure of a spring walk.

The trail through the central Commons ends on Middle Bay Road, and a quarter-mile from that road, it runs through grass on a meadow’s fringe. There, stalky milkweeds stipple the field. With my flagging tape I meant to identify a scatter of encroaching white pines that, in a few years, would crowd out the milkweed and make it their field. Soon, those now-marked pines will be cut from the meadow. By keeping the space open, we can keep the milkweed as a primary plant, and that will support the monarch butterflies that summer here.

Amid these northern milkweeds, monarchs sire the next generation, which will, when fall nears, fly to their wintering trees in Mexico. It is an astounding migratory life, lived out over three or four generations annually. Somehow, the monarchs born in Brunswick “know” to head for Mexico each year. You may have seen them on a clear September day, bearing southwest on the tailwind of a cold front’s northern breeze.

Next gen monarchs arriving in our area in early summer, seek out milkweeds and lay their eggs on their broad leaves’ undersides. Soon, those eggs hatch as caterpillars, and the leaves become their food.

The milkweeds, with their own migratory seeds shaped like a tiny heart beneath their wispy parachutes, are a crucial food in the caterpillar cycle of a monarch’s life. Milkweeds contain a chemical that, once ingested, makes the monarchs toxic to most birds, and so more of them survive to take on their thousands-of-miles migration. But, of course, this milkweed-immunity depends upon milkweed-availability. Because milkweed is an unlovely plant, except to a monarch, and because it grows in meadows, which tend to go over to forests, a natural stand of it can be uncommon and so, prized. It seems worth doing battle with our common white pines to keep this Commons’ prize.

It won’t be long before the monarchs arrive, along with the rest of our annual influx of visitors from away. The Portland-based Wild Seed Project (wildseedproject.net) offers an excellent primer (Monarchs and Milkweeds by Heather McCargo) on their website. The Project itself is also an excellent introduction to the rich world of our native plants and their habitats.

For your own sense of wonder, try a visit to this little meadow, a quarter-mile from a road amid the nearly 200- acre span of Brunswick’s Commons. It will put you in touch with its monarchs in season, with its sun-washed face amid the pines, and with its role in one of the world’s amazing migrations.

The shortest approach is from Middle Bay Road (room for one car only in the pull-off). There’s ample parking at the Town Commons lot on Rte 123 (a half-mile walk along a broad easy trail to the meadow), or, if a longer walk appeals, from Bowdoin College’s playing fields (1.5 miles, one way).

Reading Note: If, through your walking and wondering, you want more monarch stories and a fuller sense of their lives and the lives of those moved by them, Sue Halpern’s lyrical Four Wings and a Prayer (Vintage Press, 2001) is a great book. Your Land is a monthly column about open spaces to visit in our area. Sandy Stott is a Brunswick resident and chair of the town’s Conservation Commission. He writes for a variety of publications and has a book (the Art of Rescue — Chasing Trouble in the White Mountains) due out from University Press of

New England in the coming months.