Hi Andy (and others) The Cerulean Warbler is a male on territory at a traditional spot near Sycamore Landing (we have had one here for past three years). Park at the canal parking lot, and walk downstream along the tow path. In about 1/3 mile you will come to a spot where a stream passes under the tow path -- the culvert was damaged in the floods and there is orange plastic mesh fence around a large hole in the culvert, so the area can't be missed. Start listening for the Cerulean about 100 yards before this culvert and for 100 yards past -- it seems to have a rather large territory. It often sings from high in a sycamore, but the two times we have seen it it has been rather low. It will casually investigate pishing (may fly a bit lower) but mainly you will have to find it as it moves through the trees. There is also a Prothonotary on territory about 1/10 of a mile downstream of the car park. Other local spots for this species include Blockhouse Point, Seneca (behind the pond but this year we have not heard one singing) as well as Great Falls NP in Virginia. They are also fairly common in Catoctin NP, esp. on the ridge road which runs by the entrance to Camp David. Good luck! Gail