Mud-digging Northern Flickers: Wascana Park, Regina

I've always thought of Northern Flickers as tree birds not ground birds, bark drillers not dirt diggers. But when I watched several Flickers in Regina's Wascana Park on Friday, these large brown woodpeckers were spending far more time in the mud than in the trees. (And even those on the trees had muddy beaks to show that they, too, had been digging. Or they'd just finished scraping their beaks against the bark, to get them clean.) 

Northern Flicker, taking a break from dirt drilling.  © SB 

Northern Flicker resting on a tree, with muddy beak.
The line of yellow wing feathers is also visible.  © SB

Blurred, but shows the colour of these
Northern Flickers' feather shafts. © SB

What is this? A Northern Flicker (yellow-shafted); or Pic flamboyant.  
Location: Wascana Park, Regina, Saskatchewan
Photo date: September 9, 2016.

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