Geography Reference
In-Depth Information
large ones such as those preferred by pileated woodpeckers are rare—fewer
than two per acre remain.
Woodpeckers are never overly abundant; their requirement for a continu-
ous supply of standing and downed deadwood is met in only large territories.
Across their spacious ranges, however, they produce many cavities during
their lifetimes—new nest cavities each year and numerous roosts. Although
woodpeckers are intolerant of members of their own species, the defensive
drumming and calling does not repel other types. Outside Seattle, the snags
of a suburban forest can simultaneously support a pair of large pileated,
medium-sized hairy, and small downy woodpeckers. Flickers, nearly the size
of pileated woodpeckers, nest on the forest edges and feed on the ants and
ground beetles often found in grassy lawns. Sapsuckers, midway between a
hairy and a downy woodpecker in size, also coexist in this diverse cavity-
producing guild. They avoid competition with the other woodpeckers by dig-
ging nests and roosts in live trees and drilling sap wells from which they feed.
The variously sized woodpeckers provide an array of cavities that dif er
in accessibility to and suitability for other species. Flicker holes are large
enough for bluebirds but too roomy for chickadees. Pileated cavities support
red squirrels, owls, and ducks. Tiny downy woodpecker dormitories are suit-
able for chickadees and nuthatches. Sapsuckers provide cavities for swallows.
In this way woodpecker diversity magnii es overall bird and mammal diver-
sity. Even the sap wells—horizontal rows of shallow taps that sapsuckers bore
into live fruit, maple, birch, and pine trees—facilitate the biological diversity
of subirdia by providing syrupy food for a host of insects, mammals, and
other birds, in addition to the sapsucker.
Large species are often the i rst ones to be extinguished from the places
we inhabit. Living large frequently bumps them up against our activities,
making it dii cult for them to meet their needs. So the sight in my backyard of
a crow-sized woodpecker—dazzling black and white with a l amboyant, red
head crest—made me pause and wonder how this could be. How could pile-
