Story by Bryan Pfeiffer
Pity the brown creeper. A prisoner of the forest, the
creeper seems unable to escape the gravitational
pull of the tree trunk on which it creeps, ever
upward, gleaning insects, spiders, and their eggs
along the way.
Rarely does the creeper fly free or far like the
warbler, or even the woodpecker with whom it shares
life on the bark. The brown creeper is generally considered a “permanent resident” of our forests – like
the trees themselves, stuck here year-round. Squirrels
and forest moths are more ambitious in their travels.
Or so it might seem.
One fall, on Maine’s Monhegan Island, brown
creepers tumbled at dawn from the skies like
autumn leaves (which they resemble). They crept
on front lawns, on cedar shakes, and on trees
scattered throughout the forest. These voyagers
from the north help shatter our tidy notions about
birds that either stick around or migrate. Birds
sometimes do both.
Sorting out which creepers migrate and which
remain isn’t so easy, mostly because creepers seem to get little
respect – or, at least, attention – from ornithologists. Perhaps
because creepers are so cryptic, we know relatively little about
their breeding biology, including territory requirements, and
their population trends.
What we do know about creeper migration reveals a hodgepodge of movement to and from breeding grounds across North
America. Eastern and northern creeper populations, particularly
those breeding across eastern Canada, seem most inclined to
migrate. A creeper banded in Ontario later turned up 545 miles
away in North Carolina. Another banded in Massachusetts flew
262 miles to New Jersey. Elsewhere on the continent, creepers
might migrate only longitudinally (generally east or west) or
attitudinally (dropping in elevation for winter); southern populations seem to be sedentary or to move only short distances.
This kind of mixed migration pattern isn’t so unusual among
birds. Red-tailed hawks breeding here in the Northeast, for
example, either over-winter not too far away or leave us for short
periods. Red-tails from farther north sometimes migrate here to
spend at least a portion of the winter with our year-round hawks.
So what about the brown creepers now creeping around your
woods? Migrants or residents? Who knows? Finding one is hard
enough. Among the most widespread forest birds on the continent,
creepers are nonetheless inconspicuous. To find one, your best bet
is to go spishing, as we call the practice of mimicking the scold or
warning notes of wrens and a few other songbirds by repeating,
BIRDS in focus
Creepers are suckers for spishing. When it works, usually a
lone bird will fly in, land low on a tree trunk, and work its way
upward. Once your creeper gets high enough, it will fly to the
base of a nearby tree to repeat its unique foraging pattern. The
lone member of its family (Certhiidae) here in North America,
no other bird gleans like a creeper.
If you’ve been seeing creepers this past winter, they may
soon depart for points north – if they’re migrants, that is. But
fear not, other creepers may arrive to take their place. I think of
March and April – sugaring season – as creeper season here in
the Northeast. It could be that we encounter more creepers this
time of year because they’re migrating through. More likely, we
find more creepers because they begin to vocalize.
For some of us, hearing a brown creeper is like hearing tree
bark. The tumbling notes are thin and high enough to be inaudible to certain people (yeah, okay, to “older” people like me).
But if you manage to detect the creeper’s small, sweet, tinkling
song, your bird is advertising for a mate and will probably stick
around for the season.
As best we can tell, creepers don’t sing much during migration. A brown creeper singing in March is one of the first signs
that spring is indeed creeping our way.
Bryan Pfeiffer is an author, wildlife photographer, guide, and consulting naturalist who
specializes in birds and insects. He lives in Montpelier, Vermont.
The brown creeper: a life on the bark.