Northern Nesting Thrushes

     Early one sunny morning in May several years ago, I was walking in woods on a mountain in northern Berks County, Pennsylvania.  The woodland was quiet except for the ethereal, flute-like songs of a male hermit thrush.  To me at that time, that whole wooded mountaintop's existence was validated by that bird's beautiful, flute-like singing.
     Four species of closely-related thrushes, including hermit thrushes, Swainson's thrushes, gray-cheeked thrushes and Bicknell's thrushes, nest near the floors of mixed coniferous/deciduous forests of northern North America.  And, being related, they have much in common.  All these attractive species are seldom-seen recluses on forest floors and in understories where they forage for invertebrates as their cousins, the American robins, do on regularly mowed lawns.  These forest thrushes run and stop, run and stop across forest floors, picking up invertebrates to eat where they find them.  These small thrushes have similar plumage patterns, with only minor differences among the species, including brown upper parts that blend them well into the dead-leaf carpets of fallen foliage on forest floors, and make them mostly unseen phantoms on that woodland habitat during summer.  To most people, these lovely thrushes are largely unseen, unknown flutes in the summer woods.  All these woodland thrushes have whitish under parts with rows of faint spotting on their chests.  They all have big, dark, and to us, appealing eyes that are suited to seeing well in the shadows of forest understories.  And the males of each species sing lovely, heart-rending songs that are flute-like.  These thrushes are handsome, feathered spirits in the charming fern, moss and leaf-covered floors of mixed coniferous/deciduous forests they raise young in.       
     But they don't all hatch offspring in the same woods, although there is some overlap.  They have dispersed themselves into different niches to reduce competition for nesting space and food.  Hermit thrushes nest in generally mixed coniferous/deciduous woods.  Swainson's thrushes seem to prefer raising babies in conifer woods containing willow thickets.  Gray-cheeks nest farther north than their relatives and prefer habitats of stunted spruces and firs.  And Bicknell's thrushes, which are almost identical to gray-cheeks in appearance and song, nest in isolated colonies in mixed woods on mountains above three thousand feet in southeastern Quebec, Nova Scotia, the Adirondack Mountains, Catskill Mountains, and the Green Mountains and White Mountains of northern New England.   Bicknell's probably are a recent off-shoot of gray-cheek thrushes, a small population of gray-cheeks that originally settled to nest in niches where gray-cheeks do not.  Bicknell's populations expanded and flourished from there.
     Though well-camouflaged, some adults of these thrush species are caught and eaten by saw-whet owls, sharp-shinned hawks, long-tailed weasels and other predators.  And red Squirrels and blue jays are the main predators of thrush eggs and small hatchlings. 
     Hermit thrushes raise youngsters in mixed forests of northern Pennsylvania, New York, New England, across Canada and Alaska and down the Rocky Mountains.  Hermits are the only woodland thrushes that have reddish-brown tails that they regularly and slowly pump up and down, probably as a communication to other hermit thrushes.  This species winters in the southern United States and Mexico.  Some wintering individuals even visit bird feeders in winter to eat seeds. 
     Swainson's thrushes are olive-brown on top with buffy cheeks and a buffy ring around each eye.  This  species nests in coniferous forests across Canada and Alaska and winters in Central America and northern South America.  Its lovely songs spiral up and away into thin air.
     Gray-cheeked thrushes, which have gray-brown upper parts, hatch young in stunted spruces as far north as trees will grow across Canada and Alaska.  And they winter in Central America and northern South America.  Their songs are beautiful, jumbled notes that end on a higher, flute note.  
     Bicknell's thrushes are the rarest of these thrush species.  They winter on some islands around the
Caribbean Sea.
     These four kinds of secretive, woodland floor phantoms are elegant in that charming, peaceful habitat of fallen leaves, ferns and dappled sunlight.  They are quick-footed and dainty, and wonderfully camouflaged on those forest floors where they get the bulk of their food during northern summers.  And their, delicate, exquisite songs are a joy to hear in the quiet woods.  Through many years of evolving, they are almost perfectly adapted to their forest floor habitats.