Distinguishing Features
About the same size as a Robin,
the adult male is a black-backed woodpecker with a white rump and
conspicuous long white patches on the wing coverts. The head is
black with two white stripes on each side and a narrow red throat
patch. The belly is yellow. The bill is hard, straight and chisel-like.
The tail is stiff for bracing against tree trunks. The female is
very different. The head is brown with black streaks. The back,
and wings are barred black and white. Black patch on upper breast
and yellowish belly. Total length 22 - 25 cm.(Godfrey, 1986).
Distribution
Columbia Basin: Extreme southeast
Corner of the Columbia basin in the Flathead Valley and north to
Cranbrook.
British Columbia: Breeding populations
occur only in the Southern Interior Mountains, probably from Newgate
east to the Flathead River and north to, at least, Cranbrook. There
is speculation that this subspecies may be extirpated in British
Columbia (Cannings et al. In prep.).
Global: Breeds in North America,
from se. British Columbia south along the Rocky Mountains through
nw. Montana, Idaho, e. Oregon, Utah, and w. Colorado to c. Arizona
and w. New Mexico. Winters from Arizona and New Mexico south along
mountainous areas to Jalisco and Michoacán Mexico (Cannings et al.
In prep.).
Habitat
In British Columbia, Williamson's
Sapsuckers nest in mature or old-growth coniferous or mixed forests
at 800 - 1300 m elevation. Nest trees are typically recently dead,
or live with extensive heartwood decay. Little other data exists
for this subspecies in British Columbia (Cannings et al. In prep.).
Threats
Only a handful of sightings have
been reported during the last few decades. Populations are likely
extremely small. There are no data to determine population trend
but may be declining due to loss of nesting habitats. Possibly threatened
by harvesting of mature coniferous stands. Clearcuts remove
habitat, and selective logging may, or may not, be compatible. Wildlife
tree patches may be used if suitable nest trees exist (Cannings
et al. In prep.).
Biology
The Williamson's Sapsucker feeds
on tree sap from coniferous trees such as Douglas-fir or western
larch. After young hatch, diet shifts markedly to insects, especially
ants, as adults respond to the needs of nestlings. Unmated birds
continue to eat sap during the nesting season. Diet during the post-fledging
period is unknown (Cannings et al. In prep.).
Spring migrants return to British Columbia from
wintering areas in the southwestern USA from late March through
April. Nest cavities are excavated shortly after returning to nesting
territories. The nesting period extends from late April through
mid-July. Clutches are usually 5 or 6 eggs and are incubated for
about 14 days. The nestling period is about four weeks, and an average
of three young fledge per nest. Shortly after nestlings leave the
nest, adults and fledglings disperse separately from the nesting
area. Autumn migration occurs mainly from August through mid-September,
with a few stragglers occurring until mid- October (Cannings et
al. 1987, Campbell et al. 1990, Cannings et al. In prep.).
