Friday, August 29, 2014

Acorn Woodpecker

Acorn Woodpeckers are found from Oregon across the Southwestern United States, south through Mexico, Central America, to Columbia. We found a few while visiting my brother north of Silver City, New Mexico. Here they inhabited riparian oak scrubland, but, elsewhere they are also found in pine-oak woodlands. 

Acorn Woodpeckers breed in family groups of up to a dozen birds. The group members cooperatively raise their young and are famous for storing acorns in woodpecker-riddled storage trees called granaries. The woodpeckers fit the acorns into the holes they have drilled, often moving acorns to new, better fitting holes as the acorns shrink as they dry. Not all Acorn Woodpeckers, however, live in groups or use storage trees. The species also is variable in its migratory tendencies, with some populations sedentary, and others migratory.

The groups that do use granaries share their acorns as the winter progresses. Acorns are not the only items they eat—Koenig et al. (1965) also list “sapsucking, flycatching, bark-gleaning, and seed-eating."

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