14 Nebraskaland • December 2020
AN IRRUPTIVE BUT WELCOME
VISITOR FROM THE NORTH
By Stephen J. Brenner, Nongame Bird Biologist
IN THE FIELD
PHOTO
BY
SHARLA
MEESTER
For many species of birds, annual migrations and seasonal
movements follow relatively predictable patterns. This is not
to downplay the awesome feat of bird migration — flying
from South America to North America and back in the same
year is no easy task. For most species, though, these long-
distance routes are more or less the same for generations of
individuals.
Most warblers, vireos and flycatchers, for example, will
leave their wintering grounds in Central and South America to
pass through the Great Plains in spring, breed in the northern
forests of Canada in summer, and then fly back down south
and cross the Gulf of Mexico to get back to the tropics by the
end of autumn.
For some species, however, annual movements, particularly
where individuals will spend the winter, is not so predictable.
These species have "irruptive" movements between breeding
and wintering grounds that can change literally from one year
to the next. These irruptions usually occur due to limitations
or surpluses in a given species' food supply.
One of the best and most beautiful irruptive North American
species is the common redpoll. Redpolls are a quintessential
songbird of the far north, breeding in the taiga and scrub-
dominated edges of the tundra in Canada and Alaska. So why
are redpolls considered an "irruptive" finch? Redpolls (like
other breeding finches of the far north) will follow the seed
production of plants like spruce, birch and pine. And in years
when these plants struggle up north, redpolls will move south
to find greener pastures. This is why observers in states like
Nebraska see variable numbers of redpolls in consecutive
winters. In years where the seed crop up north is productive,
Nebraska hosts few redpolls, making our winters much less
colorful.
The good news — experts predict there is a good chance
redpolls will move south in larger numbers this winter. Redpolls
will readily visit feeders and could easily be overlooked when
occurring with groups of more common species, such as the
similarly sized American goldfinch. Redpolls also can be
found in birch trees and weedy fields.
Their plumage is generally frosty white with drab brown
tones featuring extensive streaking on the flanks; they also
have tiny bills. Males sport a bright red cap and even brighter
pink breast, which offers an excellent contrast to the white
plumage of their bellies and the white snow covering your
tray feeder this winter.
