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Friday, October 17, 2014

Peering and probing


Before we left Yosemite yesterday, we went on a short walk in the Mariposa Grove.  Along with the trees (which I'll talk about later), there were a few bird highlights.

I've hardly spent any time in the Sierras, so this was my first time seeing this striking black-and-white woodpecker typically associated with montane forests dominated by pines (especially Ponderosa Pines).

White-headed Woodpeckers (Picoides albolarvatus) are known for their dominantly jet black plumage, although in the right light you could see glossy bluish feathers (similar to ravens):


I read more about this species when I returned to the coast and learned that their diet includes pine seeds and invertebrates.  According to the Birds of North America account, White-headed Woodpeckers often feed on tree trunks that are furrowed or plated (containing lots of fissures).  And these woodpeckers are known for peering and probing, and flaking and gleaning, rather than hammering and boring into the bark.  The following images illustrate the peering and probing behaviors:
 


You probably noticed the small red spot (formally called a nuchal patch) on the back of this individual's head, indicative of a male.  Here's a better view of it:


We actually saw two woodpeckers, and the first was a female, lacking the red nuchal patch.  She was foraging in a place that made her more difficult to photograph, but I think it's still a decent comparison (see below).  Observations suggest that White-headed Woodpecker pairs remain together year-round.


What a way to end our trip — watching White-headed Woodpeckers weave their ways across wide trunks in wondrous woods!

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