There were large flocks of Audubon's Warblers - formerly known as Yellow-rumped Warblers, or Butterbutts (affectionately), which have now been split into Audubon's (west) and Myrtle (east) Warblers, both of which are still called Butterbutts. Anyway, these flocks were moving through California last Fall. You would hear them twittering in the treetops and see the tree was "crawling" with them. At Putah Creek I finally saw some down at more or less eye level, perhaps because they were in a treetop whose roots were quite a ways down the steep slope of the creekbank.
