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Guide to Thickson's Woods
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treasure chest of biodiversity
Guarding the entrance to Thickson's Woods is one of the oldest hop hornbeams in southern Ontario, its spreading branches indicating that it sprouted in a clearing. Its other name, ironwood, comes from the dense, extremely heavy wood of this slow-growing deciduous tree. Migrating sapsuckers drilling holes in its bark in late April reveal the other reason for calling it "ironwood"—the oozing sap turns a rusty orange.
The clearing west of the entrance, the only part of the property managed as a meadow, is often home to Blue-gray Gnatcatchers, a resting place for flycatchers, sparrows and a variety of warblers during migration.
Standing ten feet off the trail among some black cherries is a tall, slim tree with reddish bark. Because of its height, shape and forest location, few visitors would at first glance recognize this foot-thick "mystery tree"—a wild apple that produces lovely white flowers in late May, tiny yellow-green fruit in September.
A grove of bigtooth aspen along the ridge adds to the diverse mix of trees in Thickson's Woods. Look for their round, jagged-edged leaves on the ground in winter.
To preserve the pine component in the woods, baby white pines were planted in sunny clearings left by the loggers. The grove at the top of the hill sprouted on its own, shooting up from tiny green, inch-wide bottle brushes into the healthy young pines of today.
The only American beech in the woods died from stress shortly after the woods were gutted in 1983. But underground runners from its roots sent up new shoots, resulting in young trees around the carcass of the parent. Like some ironwood and oak, beech retain their warm brown leaves throughout winter.
At water's edge in early May marsh-marigolds blossom in a blaze of golden yellow.
Blue beech, a Carolinean species, never grows tall, but adds a delicate element to the understory with its striped bark and bulging growth contours that to some people look like muscles.
A pioneer species, fast-growing mountain maples were the first trees to grow up when the center of the woods was logged. Tall and leggy, they now crowd together, competing for sunlight let in when the canopy was removed. On the south ridge the forest canopy is still intact, leaving a much less dense understory.
Seeds of yellow birch often get a jump on competitors by sprouting on nutrient-rich old stumps and sending runners to the ground. Look for baby yellow birches on one pine stump near the trail, saplings on another.
Several inches thick, one of the biggest wild-grape vines in the woods climbs up an old yellow birch near the path.
Many red oaks in the woods may have sprouted from acorns produced by the massive giant growing behind a house along the west roadway. Squirrels harvest many acorns in August, before they have a chance to fall to the ground.
Around the marsh perimeter and on low, wet floodplains huge old silver poplars thrive. Look for warblers and orioles among their branches early in spring when the catkins are opening.
Red-eyed Vireos and Wood Thrushes nest in the understory shrubs in the woods--a mix of mountain maple, wild black currant and chokecherry. Carolina Wrens, a southern species on the northern edge of their range, have nested in Thickson's Woods since they first arrived late in the 1980s.
Valley of the Giants. In the SW corner tower the largest and oldest white pines in Thickson's Woods, earmarked in the last century for masts of sailing ships for the British Royal Navy. Several grow in backyards of local residents, who work with TWHF to protect forest habitat. Listen for the hooting of Great Horned Owls in February at dusk, the staccato trill of Pine Warblers high in their branches in early spring, the tick-tick-tick of Blackpoll Warblers late in migration.
Roadways to the lakeshore, owned by TWLT, are accessible to pedestrians. Please respect private property.
A rare slippery elm, a Carolinean species whose inner bark was used by native people and pioneers to prevent scurvy, grows along the west roadway near its juncture with the trail. Like basswood, it has multiple trunks.
Dying trees are as full of life as living ones. Dead stubs make apartment houses for Downy Woodpeckers, chickadees, Great Crested Flycatchers and flickers. In 1996 a pair of Red-headed Woodpeckers nested in the dead top of a sugar maple above the bird-records box.
Fallen limbs and branches are slowly broken down by fungi and various microorganisms, enriching the soil for the next generation of trees. Brush piles provide hiding places for cottontail rabbits, chipmunks and birds.
One hemlock, a climax species, joins the fringe of tall white pines left around the woods by the loggers. Three baby hemlocks planted in a nearby clearing may grow up to replace it one day.
Starflowers are a woodland species rare this far south. Trilliums throughout the woods were rescued from an Oshawa woodlot slated for development.
Red maples like to get their "feet" wet, and the only one in the woods leans out over the marsh in the SE corner near the corduroy bridge.Half the trunk is hollow and decaying, but a vigorous branch reaches up to the sunlight, producing its signature red buds in March, its magenta flowers in late April.
Peek under the knee-high umbrellas of May-apples to see their large white flowers in spring, their yellow fruit in summer.
Path rush, a short grasslike plant growing in dim light in forest clearings, lines the north ridge trail in summer. More than 375 species of vascular plants have been identified in this botanically rich area, including 17 grasses and 18 sedges.
Black cherry is a common hardwood throughout the woods, distinguished by its curling black bark. Great flocks of robins and Hermit Thrushes gather in early September to gorge on the ripening berries.
Corbett Creek Marsh supports a host of native wetland plants—and a beautiful alien invader, purple loosestrife. Meticulous hand pulling every spring keeps garlic mustard, another insidious alien, from choking native wildflowers in the woods.
