The yellow-bellied sapsucker (Sphyrapicus varius), a member of the
woodpecker family, is a migratory bird whose summer breeding range includes the
Lakes States region. The identifying field markings of adult birds are a black
crescent on the breast, pale yellow belly, white wing stripe, and a crimson
crown. The male also has a crimson chin and throat, distinguishing him from the
female whose chin and throat are white.
Although insects make up part of its diet, the sapsucker is better known for
its boring of numerous holes in the bark of live trees to obtain sap, the
activity from which it derives its name. The yellow-bellied sapsucker is the
only member of the woodpecker family to cause this type of injury. More than
250 species of woody plants are known to be attacked. Birch, maple, and hemlock
are the preferred species in the Lakes States.
|The sapsucker bores neat rows of
1/4-inch holes spaced closely together through the bark of trees along and
around portions of the limbs or trunk. As these holes fill with sap the
sapsucker uses its brush-like tongue to draw it out.
||These holes are
periodically enlarged and portions of the cambium and inner bark, together with
the fresh sap, are eaten.
Puncture wounds and resulting sap flow on branches and trunks of trees are
the most obvious symptoms of injury inflicted by the sapsucker.
attacks on the same area of a tree, large patches of bark may be removed. If
this area is girdled, the portion of tree above this point will die. Many small
limbs are killed and some- times the trunk is girdled and the whole tree is
||Sapsucker feeding on
shade and ornamental trees leaves unsightly bleeding wounds that attract bees,
hornets, and other insects to the sweet, oozing sap. On forest trees these
wounds may attract porcupines or red squirrels that further injure the trees
Early in the spring the sapsucker tests many trees around its selected
nesting site by making sample drillings before selecting ones it prefers. These
trees, because of quantity or sugar content of the sap, are visited several
times a day for the rest of the season and sometimes are used as a food source
for several years.
|Feeding wounds serve
as entry courts for a wide variety of wood decay or stain fungi and bacteria.
On high quality hardwoods, sapsucker wounds cause a grade defect called
"bird peck" that lowers the value of the trees.
||Many forest trees are attacked
high in the crowns, making light feeding wounds or sample drillings less
evident. A condition known as black bark may develop which results from certain
fungi colonizing the sap flow and discoloring the bark, and is good evidence
that injury exists. Black bands can develop on white birch as a result of a
healing reaction to sapsucker injury.
To discourage sapsuckers from
feeding on a favorite shade tree, wrap hardware cloth or burlap around the area
being tapped or smear a sticky repellent material, such as bird tanglefoot, on
In commercial forests or orchards, leave favorite feeding trees of the
sapsucker untreated. Birds will concentrate their feeding activities on these
favorite trees, which often protects nearby trees from serious injury.
Sapsuckers in search of nesting sites are especially attracted to aspen
(Populus tremuloides) infected with Fomes igniarius var.
populinus, which decays the heartwood and enables the birds to excavate
a nest hole. To protect a valuable timber stand eliminate such infected trees
within the stand during a precommercial thinning; this may discourage
sapsuckers from using the area.
The Migratory Bird Treaty Act and Federal regulations promulgated under its
authority prohibit shooting of sapsuckers. Shooting of this species would be an
ineffective control anyway because transient birds tend to replace occasional
losses to local sapsucker populations.
|MICHAEL E. OSTRY
THOMAS H. NICHOLLS
Principal Plant Pathologist
North Central Forest Experiment Station
St. Paul, Minnesota
|Produced in Cooperation With:
Wesley R. Jones
U.S. Fish & Wildlife Service
Federal Building, Fort Snelling
Twin Cities, Minnesota 55111
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