Acorn woodpecker (Melanerpes formicivorus) is a medium-sized woodpecker,
21 cm long with an average weight of 85 g.
The adult Acorn Woodpecker has a brownish-black head, back, wings
and tail, white forehead, throat, belly and rump. The eyes are white.There
is a small part on the small of their backs were there are some
green feathers. The adult male has a red cap starting at the forehead,
whereas females have a black area between the forehead and the cap.
The white neck, throat and forehead patches are distinctive identifiers.When
flying,they take a few flaps of their wings and drop a foot or so.You
can see white circles on the wings while flying. Acorn woodpeckers
have a call that is almost like they are laughing.
The breeding habitat is forested areas with oaks in the hills of
coastal areas and foothills of California and the southwestern United
States south to Colombia. This species may occur at low elevations
in the north of its range, but rarely below 1000m in Central America,
and it breeds up to the timberline. The breeding pair excavate a
nest in a large cavity in a dead tree or a dead part of a tree.
A group of adults may participate in nesting activities: Field studies
have shown that breeding groups range from monogamous pairs to breeding
collectives of seven males and three females, plus up to 10 nonbreeding
helpers. Young have been found with multiple paternity.
Acorn woodpeckers, as their name implies, depend heavily on acorns
for food. In some parts of their range (e.g., California), the woodpeckers
create granaries or "acorn trees" by drilling holes in
dead trees, dead branches, telephone poles and wooden buildings.
The woodpeckers then collect acorns and find a hole that is just
the right size for the acorn. As acorns dry out, they are moved
to smaller holes and granary maintenance requires a significant
amount of the bird's time. They also feed on insects, sap, and fruit.
The acorns are visible, and the group defends the tree against potential
cache robbers like Steller's Jays and Western Scrub Jays. Acorns
are such an important resource to the California populations that
Acorn Woodpeckers may nest in the fall to take advantage of the
fall acorn crop, a rare behavior in birds. Acorn Woodpeckers can
also be seen sallying from tree limbs to catch insects, eating fruit
and seeds, and drilling holes to drink sap. The Acorn Woodpecker
will use any human-made structures to store acorns, drilling holes
into fence posts, utility poles, buildings, and even automobile
radiators. Occasionally the woodpecker will put acorns into places
where it cannot get them out. Woodpeckers put 220 kg (485 lb) of
acorns into a wooden water tank in Arizona. In parts of its range
the Acorn Woodpecker does not construct a granary tree, but instead
stores acorns in natural holes and cracks in bark. If the stores
are eaten, the woodpecker will move to another area, even going
from Arizona to Mexico to spend the winter.
In California, Acorn Woodpeckers breed from April June. An
Acorn Woodpecker group may consist of 1-7 male breeders that compete
to mate with 1-3 females. The nest is excavated in a large tree,
which may also be a granary tree. Tree cavities are created in both
dead and living trees and snags and nest holes are reused for many
years. Females typically lay 5 eggs that are incubated for 1114
days. Male and females incubate and tend to their young. Non-breeding
helpers (young from previous years) often help with incubation and
other parental duties. The young leave the nest and take their first
flight at approximately 3032 days after hatching and return
to the nest to be fed for several weeks.
In groups with more than one breeding female, the females put their
eggs into a single nest cavity. A female usually destroys any eggs
in the nest before she starts to lay, and more than one third of
all eggs laid in joint nests are destroyed. Once all the females
start to lay, they stop removing eggs.
bird is a permanent resident throughout its range. They may relocate
to another area if acorns are not readily available. It is sedentary
and very sociable.
Acorn Woodpeckers like many other species are threatened by habitat
loss and degradation. Competition for nest cavities by non-native
species is an ongoing threat in urbanized areas. Conservation of
this species is dependent on the maintenance of functional ecosystems
that provide the full range of resources upon which the species
depends. These include mature forests with oaks capable of producing
large mast crops and places for the woodpeckers to nest, roost,
and store mast. Residents are encouraged to preserve mature oak
and pine-oak stands of trees and to provide dead limbs and snags
for nesting, roosting and granary sites to help preserve the Acorn
Walter Lantz is believed to have patterned the call of his cartoon
character Woody Woodpecker on that of the acorn woodpecker, while
patterning his appearance on that of the Pileated Woodpecker which
has a prominent crest.