I was parking my bike in the racks just south of the main entrance to UW's IMA (main gym), when I noticed 10-20(?) birds in the bushes behind the racks. The birds were Yellow-rumped Warblers doing their fly-catching behavior. I know people have been seeing them around(e.g. Scott at Mag.), but I haven't seen any in weeks and was surprised to see so many. I noticed that the air there was slightly warmer than outdoor ambient and so looked around and found a couple big exhaust air vents right next to the building. I'm not sure how much to make of proximity of the birds, bushes and vent, but I'm willing to postulate that warmth and humidity from the vents allowed insect hatches later than might otherwise have happened, and that the YR Warblers were drawn to that. Unfortunately I couldn't see what the birds were eating and just have the qualitative feeling of "warm air" in that area.

I got a great look at a Myrtle, by the way.

Darwin O.V. Alonso
University of Washington
Seattle WA 98195-7350