Last year (2014) the oaks in our area produced very few acorns. As a result the local acorn woodpecker (Melanerpes formicivorus) population plummeted. In areas where we would normally see large families of acorn woodpeckers there were none, or perhaps only one or two. I missed these clown-like birds.
This season the oaks produced large, if not abundant, numbers of acorns. The acorn woodpeckers are back in force.
While at Crystal Lake (Shasta County CA) recently I heard a cacophony of sound from an acorn woodpecker granary tree. About thirty acorn woodpeckers were flying about the granary and nearby ponderosa pines. They appeared to be “attacking” each other. When one woodpecker would alight on a branch, another would quickly push the first bird off the branch in a flurry of beating wings, all the while making their raucous calls. I have no idea what was happening, although I speculate the returning acorn woodpeckers were determining their family territories. I watched until the sun set, but the woodpeckers never stopped that behavior. These two began to tussle immediately after I snapped the picture.
On my next trip to the same granary tree all was quiet with only a few acorn woodpeckers in sight.
Our local oaks are predominantly California black oaks (Quercus kelloggii) and Oregon white oaks (Quercus garryana).