31 BIRD Watcher’s Digest • JANUARY/FEBRUARY ’ 17 • birdwatchersdigest.com
a freshly excavated
nest cavity; and, most
the male’s roost cavity
as the nest site, leaving
the male with nighttime
incubation and brooding duties. Like other
Melanerpes species, the
acorn woodpecker does
not possess the cranial
anatomy required to
regularly excavate fresh
nest or roost cavities.
Birds of this genus tend
to reuse or enlarge cavi-
ties excavated in prior
are pioneers. When a local popu-
lation appears to have vanished,
they may simply have moved to an
area with more productive habitat.
The acorn is often the most
abundant woodpecker in its range,
with the largest populations
occurring in areas with multiple
oak species, plenty of granary
sites, and a healthy selection of
standing snags. By cultivating and
conserving these habitats, we can
all be assured the long-term enjoyment of watching the clown-faced
Stephen Shunk is based in Bend,
Oregon, home to half the North
American woodpecker species.
He is the author of the Peterson
Reference Guide to Woodpeckers
of North America, Houghton
Mifflin Harcourt, 2016.
years by other woodpeckers. The
acorn woodpecker may use any
of the available cavities within the
territory of the family group, and
up to half of all groups will nest
in the same cavity used the previous year.
The sizes and breeding tactics of
family groups vary across the range
of the species, averaging four to five
birds per group. These may include
up to seven breeding males, up to
three breeding females, and up to
ten nonbreeding helpers, though
the maximum group size rarely
exceeds fifteen birds.
The life of an acorn woodpecker may sound complicated, but it
works very well for this species.
Local populations may suffer in
the short term due to habitat loss
and snag removal, but these birds S T E
A pair of acorn woodpeckers (Melanerpes
formicivorus) on a tree.