The Sanpoil River in Washington State was slipping past my legs, gurgling quietly. Earlier, a June thunderstorm had grumbled overhead and down the valley. Now it was very still.
I stood motionless, listening to the most beautiful birdsong I had ever heard, the song of a Swainson’s Thrush. And I was confused. Spiraling upward into the ether, metallic and delicate, liquid and wild, the song came from a wild rose bush a few steps away from me. Or seemed to.
I waited for the bird to sing again. When it did, the sound seemed to come not from the bush but from a location at least a few hundred yards away. How was that possible?
Minutes passed as I sloshed out of the creek bed and examined the rosebush from every angle. Finally convinced that a bird was not, and never had been, in the bush, I sat down in the sand on the riverbank.
Then I heard the same ethereal song rise out of the bush. The notes hung in the air like mist. As I stared, feathers rustled in the belly of the rosebush. The bird sounded as if it were a mile away one moment and close enough for me to touch the next. I couldn’t understand it – and I wouldn’t until I spoke with ornithologist Melissa Bowlin, international post-doctoral fellow at Lund University in Sweden.
Swainson’s Thrush, along with Veery, Gray-cheeked Thrush, Bicknell’s Thrush, and Hermit Thrush, are members of the genus Catharus. Clothed in colors that merge with shadows, fond of impenetrable brush, elusive, and vocally accomplished, they are responsible for many stubbornly empty spaces on birders’ life lists. Yet I’ve discovered that all it takes to fill such blanks is a greater understanding of the birds’ habits, preferences, and seasonal movements.
To gain this insight – and to figure out what was happening with that Swainson’s – I sought the wisdom of not just Bowlin but also two other thrush experts: Chris Rimmer of the Vermont Center for Ecostudies, co-author of accounts on the Gray-cheeked Thrush (No. 591) and Bicknell’s Thrush (No. 592) in the authoritative Birds of North America series, and Rachel Dellinger of the West Virginia Cooperative Fish and Wildlife Research Unit. Their knowledge, acquired through years of research and hands-on field study, forms the basis of the thrush-finding advice contained in this article.
Much of it is common sense. For starters, a good rule of thumb is to model your behavior after that of the bird you’re looking for. Catharus thrushes move slowly, pause frequently, stay low, stick to cover, and wear drab colors.
Translating this is simple enough: Move unhurriedly, and stay still for several minutes at each spot. Crouch or sit to lower your viewpoint, so you can look through the sparse foliage at the base of a thicket. Put on an earth-tone shirt or sweater. Sitting with your back to a tree trunk will help break up your silhouette, increasing your chances even more.
Becoming familiar with the birds’ songs is important as well, both for locating and for identifying thrushes. Each species commands a gorgeous, ringing voice and has not only a full song type that is distinctive but also a number of less remarkable, whistled call notes that Rimmer believes may function like songs.
“Knowing both the song and the call note is an advantage,” he says, “because the birds appear to sometimes use their call notes in place of a full song. We almost always hear the bird before we see it.”
Most available sound recordings include both types. Learning them can be as simple as listening to them once a day in your car on the way to work.
All five of our Catharus thrushes are strong migrants that spend the summer in North America and, excepting Hermit Thrush, winter as far away as South America. In most of the United States, therefore, the only time to see the birds is as they pass through on migration. This makes seasonal timing one of the most important considerations for adding the thrushes to your life list.
Hermit Thrush, of course, winters in the United States (and as far south as Guatemala). It does not cross the Gulf of Mexico like the other thrushes, and it is usually the first of the Catharus group to arrive on the breeding grounds, reaching the northern limit of its range the first week in May. The other Catharus thrushes trickle into southern North America in early April. Most reach their breeding grounds by early June.
With this in mind, birders looking for Hermit Thrush should focus their efforts in late March to early April in the South and from mid-April to mid-May in the North. Birders hoping for other thrushes should look from early to mid-May, depending on location. This is when the bulk of the birds will be moving through the majority of the United States. In a few special places during springtime, all five species may be present in the same woodland simultaneously.
Catharus thrushes are strongly tied to forests, but migrants use a much wider variety of wooded habitats than breeding birds. “The Swainson’s Thrushes that we studied seemed to be just as likely to land in a few trees outside a farmhouse as to land in a wildlife refuge,” notes Bowlin. “If you’re in a city or a large swath of farmland, I would look for parks or fragments of forest to start.”
Within a patch of likely looking woods, the real deciding factor is underbrush. The birds love dense brush and will rarely be found far from impenetrable vegetation of some kind. Breaks and edges are often the best, as the increased sunlight encourages the dense undergrowth where the birds forage. Proximity to water is also important, so pay special attention to areas around creeks, rivers, lakes, ponds, or sloughs. Thickets of brush along the wooded shore of a lake or pond are superb.
Our Catharus thrushes spend most of their time within such habitats very close to the ground. The birds forage by picking through leaf litter and low vegetation for insects and are most likely to reveal their presence as soft rustles and slight movements. Make sure to focus your attentions on the forest floor or slightly above it, looking for gaps in cover that provide windows through dense brush.
What hour is best
Time of day is also important, especially during migration. Catharus thrushes migrate at night, so the absolute best times of day are early in the morning and late in the afternoon. In the early hours, the birds forage actively, fueling up after a night on the wing. (This is also when you are most likely to hear them singing.) In the middle of the day, when the birds are in dense cover resting up for the night ahead, they are very easy to miss. They rev up again in late afternoon, doing last-minute feeding before taking to the skies once more after darkness falls.
Concerning migrating thrushes, Rimmer offers a word of caution for one particular ID challenge: Bicknell’s Thrush vs. Gray-cheeked Thrush. “There is too much overlap to safely separate the two visually,” he says, “so if you see one of them in their mutual migration range, you may have to just forget it.”
The solution? Gray-cheeked Thrush migrates across a broad swath of eastern North America, while Bicknell’s migrates up the Atlantic coast. The farther inland you are, the more likely it is that you are seeing Gray-cheeked.
Unfortunately, since thrushes are prone to wandering, this technique is not completely foolproof. Consequently, the best (and sometimes only) time to safely separate Catharus species is after they have reached their breeding grounds.
On breeding grounds
Although Catharus thrushes reach their breeding locations in northern or mountainous areas from mid-May through June and remain there all summer, the sweet spot is in mid-June.
This is when the birds will be most conspicuous, as they are most likely to be singing and actively setting up breeding territories. Looking for singing birds offers several advantages.
First, they are obviously much easier to detect and identify. Second, many Catharus species sing from regular perches within their territories. This makes recent sightings by other birders especially valuable, as a bird heard singing in a particular spot can likely be found again nearby. Lastly, singing thrushes tend to perch in more open areas, so as to prevent their calls from being muffled by foliage. Likely spots are open but close to dense cover and a bit more than head high – a dead branch protruding slightly from thick foliage would be ideal.
As I learned from the Swainson’s Thrush I heard singing along the Sanpoil River in Washington, however, singing thrushes have an interesting trick up their sleeve: They can adjust the volume of their song. That is, in the vicinity of a potential threat, they can sing more softly to make themselves seem farther away than they really are. Bowlin noticed this with captive Swainson’s Thrushes that she kept for her research. “It was something they would do while I was in the room and had my back to them,” she notes.
Take it from me: It’s easy to be thrown by this deception. Don’t be too sure that a singing bird is as distant as it seems.
A number of locations in North America have more than one breeding Catharus thrush. Hermit, Swainson’s, and Gray-cheeked Thrushes all breed in Alaska, for example, while Minnesota and Wisconsin’s North Woods shelter not only Hermit and Swainson’s but also Veery. And parts of New England, Quebec, New Brunswick, and Nova Scotia are home to no fewer than four thrushes: Hermit, Swainson’s, Veery, and Bicknell’s.
In locations like these, each species will occupy habitat at slightly differing elevations. Bicknell’s and Gray-cheeked Thrush, for example, will occur at the highest elevations at a given site, while Swainson’s Thrush will opt for low to mid-elevations, and Veery and Hermit Thrush tend to take over at the lowest elevations. This is hardly a foolproof identification technique, and all bets are off during migration, but it can be useful in separating such similar-looking birds.
One final opportunity to see thrushes quite well comes when the breeding season winds down. As Catharus thrushes fuel up for the fall migration, they feed busily, expanding their palate to include not just insects but also berries and fruits. Mulberry, elderberry, and other wild berries can draw thrushes out of the dense brush and into more open areas, where they may gorge on the fruit with relative abandon. Be on the lookout for locations with lots of fruit-producing plants, and pay attention to them as the season progresses.
Catharus thrushes aren’t the flashiest migrants out there, they aren’t the most colorful, and they present a stiff twofold challenge to birders: detecting the birds in the first place, and then positively identifying them, often on the basis of little more than brief shadowy glimpses.
The reward for meeting such challenges is a sighting that you will truly remember, creating a connection with the moment that easier birds just can’t match.
If you don’t believe that such plain birds can evoke such emotion, go to a forest where their songs fill the air on a summer evening. You’ll see what I mean.
10 places to find thrushes
See all 10 on a Google Map.
1 Mount Washington, New Hampshire
Bicknell’s Thrush. 6,288-foot Mount Washington is the highest peak in the northeastern United States. It is surrounded by White Mountain National Forest. Look for Bicknell’s Thrush just below treeline and breeding American Pipits at the summit.
2 Whiteface Mountain, New York
Bicknell’s Thrush. Whiteface Mountain is one of the High Peaks of the Adirondacks and was the site of the alpine skiing competition of the 1980 Winter Olympics. Conserving Bicknell’s Thrush at Whiteface Mountain.
3 Adirondack Park, New York
Veery, Swainson’s, Hermit, and Bicknell’s Thrush. The largest wilderness area east of the Mississippi River. The Adirondack Region extends from the St. Lawrence and the Tug Hill Plateau in the west to Lake Champlain and Lake George in the east, more than 6 million acres, and contains the entire Adirondack Mountain range.
4 Mount Kelsey, New Hampshire
High-elevation forests on 3,468-foot Mount Kelsey, located in Coos County, in northern New Hampshire, support Bicknell’s Thrush and other species of conservation concern, including American marten and possibly Three-toed Woodpecker.
6 Okanogan National Forest, Washington
Hermit Thrush, Swainson’s Thrush, Veery. More than a million acres of forest bordered on the north by Canada, on the east by Colville National Forest, and on the west by North Cascades National Park. Many peaks rise above 7,000 feet. The highest, North Gardner Mountain, is 8,974 feet tall.
7 Rocky Mountain National Park, Colorado
Hermit Thrush, Swainson’s Thrush, Veery. A showcase of the grandeur of the Rocky Mountains. Elevations range from 8,000 feet in the valleys to 14,259 feet at the top of Longs Peak. At least 60 mountains exceed 12,000 feet. More than 280 bird species have been recorded.
8 Glacier National Park, Montana
260 species of birds, including Hermit Thrush, Swainson’s Thrush, and Veery, have been recorded in this park, which covers 1,584 square miles and holds two mountain ranges, 200 waterfalls, and more than 130 named lakes.
9 Great Smoky Mountains National Park, Tennessee
Veery, Gray-cheeked Thrush, Swainson’s Thrush, Hermit Thrush. Ridge upon ridge of forest straddling the border between North Carolina and Tennessee. Almost 95 percent is forested, and almost 36 percent of it is old growth with many trees that predate European settlement. The Appalachian Trail passes through the center.
10 Seney NWR, Michigan
Veery, Swainson’s Thrush, and Hermit Thrush. Known locally as the Great Manistique Swamp, the refuge contains extensive wetland types and deciduous and coniferous tree species and provides habitat for ducks, Bald Eagles, Osprey, Common Loons, Trumpeter Swans, river otters, beavers, black bears, moose, gray wolves, and other northwoods wildlife.
Where to watch: Veeries tend to inhabit wetter woodlands than other Catharus thrushes and are usually found at the lowest elevations. Tangles of brush along forested riverbanks and the edges of ponds, bogs, or lakes are perfect. Look especially for green briar, rose, and blackberry thickets.
Your strategy: Search the brushy margins from within the forest to get better views into the brush, as lower light on the forest side leads to sparser vegetation. Alternatively, use a small, quiet boat to look from the water side as birds forage on the exposed bank at the base of cover. Calm June evenings are ideal.
Song: Rolling series of breezy, descending veer notes
Field marks: Upperparts uniformly reddish to tawny brown; plain face, lacks distinct eye ring; indistinct reddish brown spots; flanks washed pale gray
Where to watch: Swainson’s migrate through most of North America and are found alongside other Catharus thrushes. They are less specialized in their habitat and range and can be found in a variety of wooded habitats, so long as understory is thick. They breed in more mature conifer woods with a thick understory, typically at middle elevations and near water.
Your strategy: Listen for song in forested areas with dense undergrowth from early May onward, listening in morning and evening. Also seek out areas where they breed, and locate singing birds in evening and morning throughout summer. Swainson’s may be higher than you expect. Later in the season, pay attention to berry-producing plants, as Swainson’s can be conspicuous when foraging.
Song: Ascending spiral of whistles
Field marks: Distinct buffy eye ring; sides of face, throat, and breast washed pale buff; bold, brownish black spots; sides and flanks brownish gray to olive
Where to watch: Possibly our least-seen Catharus thrush, due to its northern breeding range, its reclusive nature, and the difficulty of separating it from Bicknell’s Thrush. Gray-cheekeds seek woods with thick undergrowth and gaps that allow you to see into the thickest growth (trails, downed trees, etc.).
Your strategy: Range is the only reliable way to separate Gray-cheeked from Bicknell’s. Search well inland from the Atlantic coast in migration. Explore potential sites early in the morning and during the last few hours of daylight in late spring, staying still and low. Listen for singing birds especially in the morning, using calls to zero in on the bird.
Song: Mostly downward series of notes like Veery’s but burry, more nasal, more complex
Field marks: Slightly larger than other Catharus thrushes; eye ring partial or lacking and whitish, never bold; plain, cold grayish face; prominent brownish black spots
Where to watch: Bicknell’s breed in fir and spruce forests in the northeastern U.S. and southeastern Canada, usually from 3,000 feet up to treeline. Regenerating and lower-stature woods are excellent, typically 5-10 years after disturbance, such as a clearcut. Areas with an extremely dense understory are crucial.
Your strategy: Bicknell’s cannot be positively identified in migration, so breeding grounds are the places to find them. Use trails and roads to search for recent clearcuts with regenerating forest. Singing birds provide the best chance of detection. Try early mornings and late afternoons in June. Learn their song and call notes. Pay attention to reports from local birding groups.
Song: Similar to Gray-cheeked, a burry, melodic series rolling from high to low to high
Field marks: Much smaller, on average, than other Catharus thrushes; more yellow on lower mandible than Gray-cheeked; very similar to Gray-cheeked Thrush
Where to watch: Familiar Hermit Thrushes will occupy more open areas than other Catharus thrushes but still close to dense cover. Look in more sheltered ravines and moister woodlands in winter and near openings in a variety of forest types in the breeding season.
Your strategy: Focus searches around natural openings, such as clearings, recent burns, landslides, or tree falls. Hermit Thrushes utilize a variety of habitats, can show up nearly anywhere, and often venture out of cover. They migrate earlier than other thrushes, starting in late April. Look for breeding birds in lower-middle elevations in the Appalachians, higher than Veery but lower than Swainson’s Thrush.
Song: A single flutelike note followed by a fast, quavering warble
Field marks: Thin, whitish eye ring; rufous tail contrasts with upperparts, distinctive habit of cocking, then slowly lowering tail; only Catharus thrush that winters in North America
Chris Duke is a nature writer based in Seattle who has worked as a wildlife biologist for the World Parrot Trust in Bolivia. He wrote about finding Oporornis warblers in our June 2009 issue. He thanks ornithologists Chris Rimmer, Melissa Bowlin, and Rachel Dellinger for sharing their knowledge and experience to make this article possible.