The Yellow-rumped Warbler (or Butterbutt, as birders sometimes fondly refer to it) is not only a great bird, but it’s a great Audubon bird. Here’s why: For a long time, the Yellow-rumped Warbler was considered two species – the Myrtle Warbler in the East, and the Audubon’s Warbler in the West. While there are people who talk about the two separately, which is kind of easy to do as their geographic differences are pretty noticeable. But here in California, both “kinds” of Yellow-rumped Warblers winter here, although the Mertyl-type tends to stick more to the coast and head much further north in the spring to northern Canada and Alaska, whereas the Audubon-type tends keeps it a little closer to home in the spring, heading to the Pacific Northwest and Canada, mostly on the western side of the continent. But, for all intents and purposes, we’re talking about the same bird, and this writer would be hard-pressed to tell the difference. In terms of spring migration, the bird is kind of a late departer. According to the most recent eBird map, they're still in California in decent numbers. Most Yellow-rumped Warblers are going to be heading out to breeding territory by late-April and early-May. So they should be lifting off pretty soon. (photo by Dave Menke/USFWS)