So, the first jolting discovery of my North Woods sojourn was that my patch was not what I thought it would be. I’d assumed I would be in the heart of a mature spruce-fir forest, but instead I was in a monoculture of scrubby and fire-prone Jack Pine. Based on research I had done at the National Fish and Wildlife Foundation, I knew Jack Pine was a strange and stunted little conifer required as breeding habitat for the endangered Kirtland’s Warbler. I had driven earlier through Jack Pine barrens in northern Wisconsin, and had understood why the pine gets no respect: it is short and often irregular in shape. It is a poor timber tree. And it tends to burn up in forest fires before growing very large.
This barren landscape was now my temporary home, and I ventured out farther from my campsite as the days passed and the summer solstice drew near, giving me more than sixteen hours a day of daylight: a lot of time for naturizing. And I needed it. The Jack Pines’ dominance meant that I had to search for each new animal I saw: few birds sang in this great expanse of piney scrub. The birds that summer here occupy the forest in vanishingly low numbers.
The Ruby-crowned Kinglet was the most common long-distance migrant inhabiting the monoculture: wherever I went, I heard its high, bubbling crazy quilt of a song, one of the few I recorded every day in the North Woods. The energetic little songbird nervously foraged in the needles of the Jack Pines, usually on upper branches, with flicking wings and herky-jerky movements.
Second only to the kinglet in the pines was the Gray Jay, an iconic bird of the North Woods, which I also recorded each day. This nonmigratory, year-round resident is very different from the more familiar Blue Jay, which does not range this far north. The Blue is migratory, quite vocal, and wary, whereas the Gray is nonmigratory, quiet, and tame. The very plain Gray Jay somehow manages to survive the brutal winters and nest productively in the North Woods. Adults form pairs that stay together year-round. Nesting in early spring, they produce two or three blackish young that hang out with their parents for much of the late spring and summer. Family groups of Grays emerged from the forest to investigate me as I passed by on my bicycle, showing no fear and allowing a close approach. It is hard not to like these whimsical and confiding birds in this lonely land.
Three other birds do fairly well in this Jack Pine landscape: the Common Raven, American Robin, and Northern Flicker. I observed the three most days when I cruised the Nord Road through the vast stands of Jack Pine. The raven is our largest songbird, a year-round resident of the North Woods, and it is one of those birds that moves far and wide rather than being a habitat specialist; it tolerates the Jack Pine landscape but can use many other habitats to survive. Here the ravens moved up and down the Nord Road in search of roadkill and other carrion, and the opportunists were hyperabundant at the Musselwhite Mine, where flocks of the big black birds hunkered on every available perch, reminding me of ominous scenes in Hitchcock’s The Birds.
The robin, that familiar backyard songbird, loves wilderness as much as suburban neighborhoods, and I found it in small but decent numbers in the Jack Pines. Here in the North Woods, it is a summer visitor; these northern populations winter south into the United States. The bird has very broad habitat tolerances and, like the raven, is able to make a living in just about any wooded environment, which makes it one of North America’s most successful songbirds.
I spotted the Northern Flicker in small numbers in the Jack Pines; this woodpecker is another commonplace North American species that breeds from Alaska to south Florida. As with the robin, the flicker is a summer breeding visitor to the North Woods, here foraging in the clearings created by the Nord Road. It winters south into the Lower Forty-eight.
During my stay in the North Woods, I occasionally encountered other birds in the Jack Pine monoculture—Myrtle Warbler, Tennessee Warbler, Golden-crowned Kinglet, Red-breasted Nuthatch, Ovenbird, Hermit Thrush, and Dark-eyed Junco—but most of them were more common in other wooded habitats. The Myrtle Warbler, alternatively known as the Yellow-rumped Warbler, lives in the northern spruce bogs as well as the pine barrens, and it became the first quest species I saw in Ontario. The species is an annoyingly common passage migrant in spring and fall in the Mid-Atlantic: flocks of this bird can swamp out other warblers during migration. Moreover, many Myrtle Warblers winter along the East Coast in coastal scrub, where they are one of the more common species of birds in the dark of winter. They are one of the few warblers to subsist on fruit in the U.S. winter, eating the fruit of Bayberries and Wax Myrtle. The male sports a yellow crown-spot, flank patch, and rump, which highlights its black, gray, and white plumage. The species breeds in conifers and sings its feeble musical warble from atop conifer spires.
Yet wherever songbirds are few in a habitat, hearing a Myrtle Warbler in song is reassuring. The Jack Pine forest was an ornithological dry hole, but perhaps I would find my migrant songbirds in the two other habitats: the spruce bogs and the aspen groves.
BIRDING THE SPRUCE BOGS
The patches of forest that featured spruce, fir, and Tamarack proved to be birdier habitat, and I found them mostly in the boreal bogs. I’d known and loved such areas during my years spent in the Adirondacks, where the specialty boreal birds that I knew lived in spruce bogs. It was thus clear that I needed to search out and spend as much time as possible in bogs here in northern Ontario.
A typical spruce bog settles into a depression in the bedrock that traps water. Usually at the bog’s center is a pond that is being gradually encircled by a mat of Sphagnum moss, which can grow in dark, acidic water. The acidity is created by the chemistry of the parent rock and by the annual deposition of conifer needles. Year after year, the Sphagnum adds layers and sinks into the water, forming a flat mat (called peat) that thickens and that creeps ever closer to the center of the pond. Acid-loving shrubs start to colonize the growing mat of Sphagnum, and then the bog-loving conifers (Black Spruce, Tamarack) follow, growing on the driest outer perimeter of the Sphagnum mat and encircling the pond.
From above, a mature spruce bog reveals itself: the small pond is surrounded by a broad ring of Sphagnum, encircled by various bog-loving shrubs (Labrador Tea, Bog Laurel, Sheep Laurel, Dwarf Huckleberry, Leatherleaf), surrounded by rings of ever-larger conifers, the most mature and tallest of them on terra firma, at the outer edge of the depression. Thus a classic spruce bog has an exquisite natural design. Nature then throws in a number of unusual small herbaceous plants—pitcher plants, sundew, and various orchids—just to make things interesting for botanists.
Bogs come in many other shapes, too, not just the typical circular form. They can arise when a receding glacier drops a pile of rock as a moraine that blocks a valley, causing flowing water to fill the depression. In some places, vast planar boglands can form without a central pond. Instead they hold an open Sphagnum mat, dotted with tiny spruce and tamarack trees, that stretches across the landscape.
Along the Nord Road, a mix of bogs and boglands is scattered within the Jack Pine landscape. Here the finest boreal conifer forest grows on morainal edges of bogs where the soil drains better and where the trees are protected from the periodic fire that sweeps through the Jack Pines every few decades. The great fires burn patchily, destroying some areas and entirely missing others. Spruce, fir, and Tamarack are not fire-tolerant species, and so these blazes, along with other periodic disturbances and varying groundwater availability, create the patchwork of forest types I saw here. In this area, spruce bogs occupy about 15 percent of the land cover, and thus I had plenty of territory to explore, which I did day after long day.
As noted, the spruce bogs of the North Woods resembled those I knew from the Adirondacks. Because the big ice sheets that trundled over these lands also made their way down to the present site of New York City before retreating, the youthful boreal woodland flora in New England and northern Ontario are very similar, and both are species-poor. Black Spruce and Tamarack, which populate bogs in the Adirondacks, also populate the bogs in the North Woods.
Spruce Grouse
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Here along the Nord Road, Tennessee and Magnolia Warblers sang from tall mature conifers that grew around the bogs’ outer verges. Hermit Thrushes and Swainson’s Thrushes sang their beautiful songs from the dark recesses of the conifer stands, where Winter Wrens bopped about and launched into their virtuoso song solos from thickets and blowdowns. Golden-crowned Kinglets foraged quietly in the top branches of spruces. White-throated Sparrows hid in shrub thickets at bog edges and sang their sad “Old Sam Peabody” song. The occasional tall, dead spruce snag would host an Olive-sided Flycatcher, singing his quick-three-beers song every now and then. It was a wonder to watch this rare flycatcher launch out high into the air in pursuit of some distant flying insect.
Two other, smaller flycatchers frequented the spruce bogs, too. The noisiest was the Alder Flycatcher, which sat atop Speckled Alders in wet spots in the bogs. This drab flycatcher gave its burry wee-BEE-oh several times a minute, flicking its wings. The Yellow-bellied Flycatcher, a conifer specialist, usually hid in the spruces and firs to give its soft chee-bunk or sometimes a liquid per-wee call. The bog songbird with the prettiest voice was Lincoln’s Sparrow, whose sweet series of various trills carried far and gave away the location of this very shy shrub-dweller, typically seen hiding nervously in the center of some bushes.
The Tennessee Warbler (discussed at length in chapter 1) was one of the quest birds that I found in the spruce bogs. In fact, it was the most common wood warbler here. I saw and heard it daily, and wondered why this species abounded here when other warblers did not. This is a question I never have answered.
Two of the open-bog specialists were Nashville Warbler and Palm Warbler. These handsome yellow-washed wood warblers flitted about in the tops of isolated Tamaracks and spruces scattered across the mats of Sphagnum, their loud songs giving them away. The Nashville Warbler is one of the more common and widespread of the boreal wood warblers (we discussed the species back in chapter 2, at the Mad Island banding station). It breeds from eastern Canada and New England west to California and north into Canada. One of the smallest wood warblers, it is a relentless songster, perching atop some conifer in the open and belting out its series of trills and slurs. It prospers in bogs and conifer openings, though it was uncommon here in the far north.
The Palm Warbler, the commonplace vanguard spring migrant along the East Coast, is a true bog specialist—even more so than the Nashville. Eastern populations of the Palm Warbler, which winters from North Carolina to Panama, exhibit a red-brown cap, yellow underparts with red-brown streaks, and an olive back and wings. It exhibits two distinctive habits: tail-wagging and spending a lot of time foraging on the ground in openings in fall and winter. The species rarely makes the top ten most-wanted warblers, mainly because it is a very frequent seasonal migrant throughout most of the United States.
The crown jewel of spruce bog songbirds is the Connecticut Warbler. One morning while biking, I heard the staccato song of a male Connecticut Warbler on territory at the back of a small bog surrounded by tall Tamaracks. I drew him out by playing a recording of the species’ song from my iPhone attached to a small speaker, and photographed him while he darted about in the shade. Many birders in the United States say the Connecticut Warbler is one of the most difficult wood warblers to see. It is not terribly rare, but its northern breeding range is out of reach for most, and during migration it is very elusive. I spent years hoping to encounter a Connecticut Warbler in the autumn at Cape May, New Jersey. The closest I’d come was when birding expert Michael O’Brien once called out, “Connecticut Warbler!” while pointing to a tiny bird passing overhead in the wind at Higbee Beach. I could barely even discern that it was a warbler at all. But here in Ontario, I had my first good, long look at a singing male Connecticut in full view, unobscured by vegetation.
During the breeding season, the Connecticut Warbler is sparsely distributed in Black Spruce–Tamarack bogs from the boreal zone of northwestern Canada to the Upper Peninsula of Michigan. It winters in northern South America. During spring migration, these furtive birds migrate up through Florida and then west of the Appalachians to the North Woods. In autumn, they move southeast to the New Jersey coast and then out across the Atlantic to northern South America (more on that migratory feat in the last chapter). Most U.S. birders search for this bog specialist in northern portions of Minnesota, Wisconsin, and Michigan, but the hunting is tough: at the southern fringe of its breeding range, this species is few and far between. One aspect of the species life history does give an advantage to the birder: the male’s territorial song, a loud and rapid series of chippy chuppy notes that carries a considerable distance and is most similar to that of the Northern Waterthrush.
Day after day I hunted the tall, bog-fringing spruces for signs of either Bay-breasted or Cape May Warblers and listened for their high-pitched songs. No luck. Noisy and widespread Tennessee Warblers sang from the tall conifers at the edge of every bog, but many of the expected wood warblers were nowhere to be seen. Though disappointed, I did manage to continue to pick up odds, ends, and surprises. One day a flock of Cedar Waxwings zipped overhead. A few pairs of tannin-stained Sandhill Cranes nested in some of the larger boglands, and their bugling sounded in the distance from time to time. This haunting voice, heard mainly at a far remove, is the song of the wild. In larger bogs, I occasionally flushed out a Wilson’s Snipe, a boreal-nesting shorebird that forages in wet grasslands and explodes out of the grass with loudly voiced expletives, causing the flusher to leap backward and gasp. Once on the wing, the bird rapidly zigs and zags across the sky and just as quickly drops back into another patch of boggy grass. One rarely gets a good look at this long-billed, speckled, and striped nonpasserine. And Blue-headed Vireos sometimes appeared in small clearings, foraging atop a conifer.
HOMING RIDDLES FOR THE SONGBIRD MIGRANTS
How did these singing Blue-headed Vireos in the bog edges get to their little patches of Ontario from their winter home in Central America? Just how these songbirds succeed in traveling thousands of miles from their southern haunts to pinpoint their summer nesting site remains mysterious. Since they fly at night and at great altitude, their guidance systems must in some way approximate those of a modern airliner, with the ability to sense various geographic clues to aid their steering. As mentioned earlier in the book, a navigating bird must have analogs to a map, a compass, a calendar, and a clock, as well as a good memory, to make its annual round-trip from the Tropics back up to Canada. Research over the past half-century has enumerated the considerable detection skills that birds use in their navigation to distant fixed destinations. These include the following:
1. the ability to detect compass direction from the position of the sun
2. the ability to detect ultraviolet light
3. the ability to determine the plane of polarized sunlight
4. the ability to detect the earth’s magnetic field
5. the ability to hear ultra-low-frequency sound
6. the ability to determine compass direction from the rotation of constellations in the night sky
7. the ability to detect latitudinal position by the seasonal position of particular constellations or through the level of magnetic declination
These, and as-yet undiscovered capacities, enable birds to accomplish their biggest migratory task: locating their nesting sites after eight months away from their northern homes.
Translocation studies show that adult birds of many species, when captured, moved, and then released far from their home territories, are able to make their way back to their nest sites in short order. For instance, an adult Laysan Albatross taken from its nest and released three thousand miles away was able to make its way back to its nest in only ten days—traveling an average of three hundred miles a day. By contrast, young birds are unable to accomplish such a feat. The precise mechanism of target-oriented navigation remains unknown, but certainly it involves the tools listed above and probably additional ones not yet discovered.
How does o
ur Blue-headed Vireo locate the thicket it was born in after a winter in Colombia? Study of different migratory species, thrushes, has shown that once northbound birds reach the latitude of their natal territory, they begin making east-west flights to track down their home. These flights might allow the birds to detect familiar visual landmarks as well as characteristic low-frequency sounds produced by mountains, rivers, and coastlines. The birds also may employ their sense of smell to “sniff” out familiar landscape smells that emanate from the natal territorial (a spruce bog, for example, smells quite different from Jack Pine forest). Using their sharp memory, they might be able to recognize particular landscape features from high in the sky. We know some of the detection tools they deploy, but we do not know which specific tactics the Blue-headed Vireo uses, or how it uses them, to return to its little breeding patch.
BIRDING THE ASPEN-POPLAR GROVES
The third wooded ecosystem here in the northlands is the aspen-poplar grove. This broadleaf habitat prospers in soils of deep gravel on well-drained upland sites. Quaking Aspen and Balsam Poplar—rapid-growing early successional members of the poplar lineage—dominate these groves, which here grow up mainly in the clearings that road crews created when they quarried gravel to build the Nord Road. These patches of mechanical disturbance quickly revegetated in shrubs and the two species of poplars, areas that I spent time in to find songbirds that favor deciduous trees amid the vast conifer barren.
After my success in bringing in the Connecticut Warbler with a playback of its song, I started to use the same technique to search for other elusive songbirds. Since aspen groves are a favored habitat of the rare Philadelphia Vireo, I played its song when I visited the aspens, and I managed to draw in both the Philadelphia and the more commonplace Red-eyed Vireo. Earlier in the book I had noted that the songs of the Red-eyed and Philadelphia Vireos are difficult to tell apart, and it seems the birds themselves have this same difficulty. The Red-eyed is the more handsome of the two, with its distinctive dark facial pattern, clear white underparts, and larger bill. The Philadelphia, short-billed and exhibiting a distinctive strong yellow wash on the throat, otherwise looks like an undersized Red-eyed.
North on the Wing Page 18