Thursday, February 21, 2008

Acorn Woodpecker--Melanerpes formicivorus

Male Acorn Woodpecker clinging to a utility pole used as a granary (storehouse) tree for its family group. At Irvine Regional Park in the City of Orange.

Acorn Woodpeckers are part of the history of Orange County. They are closely connected to mature Oak Woodlands. Oak Woodlands are part of the larger landscape of California. In the report Oak Woodland Bird Conservation Plan, it states that "Oak woodlands have the richest wildlife species abundance of any habitat in California, with over 330 species of birds, mammals, reptiles, and amphibians depending on them at some stage in their life cycle." That type of habitat is a habitat worth preserving. The mature oak woodlands in Orange County are important to our wildlife. Irvine Regional Park , O'Neil Regional Park, Santiago Regional Park and wilderness areas preserve these precious oak woodlands for the future generations of Orange County. Acorn Woodpeckers are an integral part of our Oak Woodlands.

Acorns and the mistletoe that grows on the oaks provide food for many birds including Wood Ducks, California Quail, Western Blue Birds, Scrub Jays, Phainopeplas, Steller's Jays, Nuttall’s Woodpeckers, Lewis Woodpeckers, and Acorn Woodpeckers. The large, mature trees provide homes for both cup-nesting species and cavity-nesting birds, and the large branches cover for many other species.

Acorn Woodpecker Granary Tree in Irvine Regional Park in Orange, California .

Acorn Woodpeckers are found most often in mixed oak woodlands and seem to like the oak woodlands that have pine trees the most. They rely on acorns in the winter that they have stored in holes they've drilled in tree trunks and other large objects. These trees pock-marked with thousands of holes are called granary trees. The softer pine trees make great granary trees in which to drill holes and store acorns. The Acorn Woodpeckers also store acorns in mature oaks with thick bark, dead oak trees or oak-tree limbs, phone poles, in building walls, under roof tiles, pine cones, and even in boulder crevices or in softer stone that they drill holes in. I heard one story of a house in an oak woodlands that had a wall opened for repairs only to find it packed with acorns. In the All About Birds article, it tells of a a wooden water storage tank that was stuffed with 485 pounds of acorns by a colony of Acorn Woodpeckers. But mostly it is trees are drilled and stuffed with acorns. Some of the oak trees are over a 100 year old, and a granary tree may be used for generations and generations of Acorn Woodpeckers. It is a valuable cache to be guarded, and this food larder keeps the colony of Acorn Woodpeckers in the local area all year long.

A closer look at the granary tree.

The Acorn Woodpecker is often called the "clown bird" because of its bold red, white, and black patterns which are reminiscent of circus clowns. The white eyes stand out against the black sides of its head. Its wings also have bold patterns of black and white like many woodpeckers. The female has a black stripe on her forehead between the white and the red. The male has only white and red on the forehead. The immature looks has no black stripe and has a dark eye. It has a loud, raucous call that draws attention to it. The call is variously described as "waka-waka-waka" (All About Birds), "Waka" (repeated) by National Geographic's Field Guide, "wheka, wheka or RACK-up, RACK-up" (Sibly), and "ja-cob, ja-cob", "wake-up, wake-up" (What Bird). You get the idea. And it's loud. Did I mention that?

Acorn Woodpeckers eat lots of acorns and other nuts such as pecans. They also eat insects which they catch either in the air like a flycatcher or which they pick off the leaves of the trees in the woodlands. They also gather to drink the sap from holes they drill for that use. The holes are used for years. Acorn Woodpeckers also eat fruit and oak catkins (flowers), and flower nectar. They also will eat nestlings, eggs, and bats. Though these last three are uncommon. By far, the favorite food seems to be acorns.

Oak Canyon Nature Center

Acorn Woodpeckers are a group kind of bird. They breed and raise their young in groups. There are two or so female Acorn Woodpeckers that mate and lay eggs. There about 1-7 males that mate with the 1-3 breeding females. The rest of the Acorn Woodpecker Colony take care of the young. Beyond breeding season, the birds still stick together for warmth and to guard their food sources. Other birds like chickadees and Scrub Jays steal their acorns out of their granary tree. So the colony needs to make sure they are watching the cache of acorns by watching and defending the granary tree. Similarly, they watch the sap trees that they have drilled sap wells into. Other woodpeckers and Allen's Hummingbirds are very interested in the sap wells drilled by Acorn Woodpeckers.

Oak trees at Oak Canyon Nature Center in Anaheim Hills.

In addition to being loud and raucous, the gregarious Acorn Woodpeckers are also somewhat aggressive. They vie for top breeder by getting rid of and eating the other females eggs. And they can eat nestling and even bats on occasion. These are not shy retiring birds. The competition for top breeder can become brutal.

Acorn Woodpecker on a Granary Tree that is a Phone pole. His short little legs make it easy to stay close to the pole as he climbs.

Acorn Woodpecker range depends a lot on available food. It is a Western Bird. It is resident in Western Oregon, California, New Mexico, Arizona, western Texas, Western Mexico, and south through Central America, with a sprinkling of Acorn Woodpeckers in the Andes in Columbia. It is rare in Washington and there is a tiny area where they are resident in Southern Washington.

There are lots of great places to see Acorn Woodpeckers in Orange County. Check out the links below and you may find a place near you where you can see Acorn Woodpeckers. They are fun to see. Have a great time birding in Orange County! Don't miss the loud and rowdy Acorn Woodpecker.

You Tube Video of a White-breasted Nuthatch stealing an acorn from granary tree.

Places to Find Acorn Woodpeckers

Places you would find Acorn Woodpeckers would be areas with lots of oak trees. Some of these would be:

(Wooded areas with oak trees or near such an area. Areas by the ocean or grassland areas with no oaks will probably not have Acorn Woodpeckers.)

Carbon Canyon Regional Park

Donna O'Neill Land Conservancy

Laguna Coast Wilderness Park

Notice the stiff tail feathers that help woodpeckers as they climb trees.

OC Birder Girl Links

Checking the acorns. Male Acorn Woodpecker.

External Links and Resources

All About Birds from Cornell Ornithology Lab
Informative and thorough article about the Acorn Woodpecker includes range maps, behavior, reproduction, diet, photos, and sound.

Detailed, article with lots of good information about especially about their diet, behavior, habitat, and conservation status. Covers economic impact on humans.

Article from the Audubon Society of Seattle. Washington is at the Northern edge of the range of the Acorn Woodpecker.

Good Article--or at least part of it that gives some good information about the Acorn Woodpecker.

Organization about the protection of oaks in California. Lots of information.

Enhancing Oak Woodland Habitat for Birds at Your Home or Ranch

About preserving Oak Woodland Habitat on your own land.

Good information on Oak Woodlands from UC Davis' Hasting Reserve where there is an on-going 37-year research project on Acorn Woodpeckers.

Oak Woodland Bird Conservation Plan
California plan to preserve Oak Woodlands and the birds that depend on them.

Short article on the Acorn Woodpecker. Photos. Don't forget to click the links at the left of the USGS page for more information.

Great Bibliography of websites on the web.

Helps people develop wildlife habitat on their land.

Notice the white on the forehead. Females have a black area between the red head and white forehead, so this is a male.

Journal Articles

(Western Birds: Vol. 35, No. 1, 2004) Yuk. Laine MacTaguetells us about Acorn Woodpeckers that sometimes eat bats.

Journal article from The Condor about hummingbirds drinking the sap from holes drilled by Acorn Woodpeckers.

(Auk: Vol. 116, No. 1, January-March, 1999) PHILIP N. HOOGE, MARK T. STANBACK, and WALTER D. KOENIG talk about what type of sites Acorn Woodpeckers on the Hastings Reserve tended to pick and speculate why. They also tell us which types of nest sites where most successful.

Energetic Benefits of Communal Roosting by Acorn Woodpeckers During the Nonbreeding Season
(Condor: Vol. 96, No. 3, May-June, 1994) Those scientists from the Hastings Reserve share their research and thoughts about the benefits of communal living all year long for Acorn Woodpeckers.

Food Storage By Acorn Woodpeckers at the Santa Rosa Plateau Preserve, Santa Ana Mountains, California
(Western Birds: Vol. 23, No. 4, 1992) Scientists from Southern California share where and what Acorn Woodpeckers at the Santa Rosa Plateau have been storing.

Acorn Woodpecker Predation on Cliff Swallow Nests

(Condor: Vol. 89, No. 1, January-February, 1987)

Foraging Behavior of the Acorn Woodpecker in Belize, Central America

(Condor: Vol. 83, No. 4, July-August, 1981). Various ways Acorn Woodpeckers find and gather food.

Acorn Woodpecker on a telephone pole at Oak Canyon Nature Center in Anaheim Hills trying to decide which hole gets the acorn


Good quality videos.

Great short video about Acorn Woodpecker's habit of storing acorns. Followed by other generic bird videos from National Geographic.

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