I encountered a small flock of Bushtits (Psaltriparus minimus) in a willow thicket in the late afternoon today (20 February 2023). They were so covered in pollen that at first glance I thought they might be warblers!
Here's another individual:
And the Bushtits weren't the only ones —
here's a Chestnut-backed Chickadee (Poecile rufescens) dusted with so much pollen that its belly is golden: