I was on the North Tract of the PRR this AM about 0830 at the Wildlife Viewing Area and observed a flock of about 20 Bluebirds, associated with these were up to 8 Pine Warblers. They moved from tree to tree with the Bluebirds and even feed at the edge of the gravel road with them for the time I was there (about 30 min). Then about a hour later I saw a smaller flock of Bluebirds at Lake Allen with 3 Pine Warblers mixed in. Has anyone seen this behavior before or is it just coincidence? Other highlights- 8 warbler species, including Nashville on the River Trail, "grey-cheeked" thrush, 6 woodpecker species, first White-throated Sparrow of the fall, and (family of ?) 4 Brown Creepers. I may need to take off my glasses to read my Peterson's, but I can still hear their calls. Tom Beal Glenn Dale, MD