The Picidae bird family is adapted to tree life. It lives in oak and pine woodland forests. Toe arrangement is ideal for bark gripping, beaks are styled for pecking, long, sticky tongues are good for catching wood-boring insects, and skull size and orientation prevent brain impact injuries. Picidae species include; woodpeckers, the northern flicker, and sapsuckers.
This article focuses on family commonalities, then concentrates on acorn woodpecker behavior patterns.
Woodpeckers are an indicator species for healthy oak woodlands.
Woodpeckers, flickers, and sapsuckers inhabit areas with multiple oak tree varieties because each type produces a different amount of nuts per year. Acorns dropped by woodpeckers aid in tree proliferation.
Picidae feathers are mostly black and white with red highlights. Males and females can be identified by head plumage. (In the Resource section below, you’ll find bird call and feather pattern identification links.)
Spring, Summer, and Fall Diet:
- oak flowers
- wood-boring insects (*Black-backed woodpecker specializes in eating wood-boring beetles that emerge after a forest has burned.)
- hoarded acorns, nuts, and insects
Predators & Food Thieves:
- Blue Jays
- Mule Deer
Drumming – proclaims territory and attracts a mate during mating season.
Usually occurs during March through June mating season.
- Physical – netting, sheet metal, filling holes
- Scare Away – bird-of-prey statuettes, twirlers, and brightly colored plastic strips
- Building prevention – light colored siding made of aluminum or vinyl
- Other control methods – bird feeding stations, nest box placement, offering poles and other granary sites.
Migratory Bird Treaty Protection:
Woodpeckers are protected under the Migratory Bird Treaty Act of 1918. ”All woodpeckers are protected under the Migratory Bird Treaty Act (MBTA). This law says: “No person may take (kill), harass, possess, import, export, transport, sell, purchase, barter, or offer for sale, any migratory bird, or the parts, nests, or eggs of such bird except as may be permitted under the terms of a valid permit…” Control methods that do not harm the bird or an active nest are allowed for most species.” -U.S. Fish & Wildlife Service. (See link below).
Acorn Woodpecker – Melanerpes formicivorus
The industrious acorn woodpecker may be best known for constructing granaries. A granary, also known as a ‘mother’ or ‘pantry’ tree, is an older tree with thick bark. Borehole depth doesn’t spill sap that would spoil the nut.
A snag or telephone/power pole can also serve as a pantry.
Granaries are built by multiple generations of bird families. They require constant maintenance. As nuts dry, they shrink, causing them to loosen. A loose nut can be stolen, so acorn woodpeckers move them to smaller holes and continually check for tightness.
Gathering more nuts than is needed is known as hoarding. Hoarding is used to remain in place year-round.
A single bird can gather up to 100 nuts per day in a harvesting territory that ranges between 12-15 square miles.
Family Social Structure
Acorn woodpeckers are highly social. Family units can be as large as fifteen. Usually there are several mating pairs with the females sharing a sister relationship. Grown children or siblings remain in the group to care for young and maintain granaries.
Females use a joint nest, laying all their eggs in the same hole. (As egg laying begins, a female entering a nest with eggs already in it will destroy some before laying her own.)
Cooperative behavior (adult birds opting not to reproduce) is an usual phenomenon that has been the subject of a long-range study by UC Berkeley and Cornell University scientists.
If you liked this story, you might also like California Quail – Happy Under Cover.
Have you observed Picidae in Nevada County not mentioned in the article? If so, please leave a comment in the comment section below.
Bird Calls & Plumage Identification
All About Birds Articles
Cornell Cooperative Extension – Woodpeckers – Wildlife Damage Management Fact Sheet (PDF)
Cornell Lab of Ornithology – Walt Koenig’s Lab
Book – Population Ecology of the Cooperatively Breeding Acorn Woodpecker by Walter D. Koenig
Stanford Magazine – Full Life with Woodpeckers
University of California Agriculture & Natural Resources – Statewide Integrated Pest Management Program – Woodpeckers
U.S. Fish & Wildlife Service – Migratory Bird Treaty Act of 1918
U.S. Fish & Wildlife Service – Woodpeckers – Inflicting Damage on Property (PDF)
Massachusetts Institute of Technology – How Woodpeckers Avoid Brain Injury