1977 Walter D. Koenig Melanerpes formicivorus 3 (20 April) Y Hastings Reservation foci of activity, while there are probably 4-6 other independent intruders either in one or the other of the core areas (and thereby being chased) or in one of a couple of peripheral trees, where he/she is sitting and Carrickling rather frequently. 945. There is yet to be any "interchange" between the 2 sets of (birds) here. For the record, this area had been completely at ease until this morning. Later in the afternoon I returned briefly and noted the barn area quiet and almost completely dominated by Y birds; several 1500-types (including possibly 8/95) were still up on the knoll where there was still some chasing and excess activity. As for roosting. Here: when I first watched at dusk here last week from the knoll, I was quite impressed by the fact that all 4 birds gathered rather quietly in the locusts and then right as it got dark all split virtually simultaneously in a tight flock as I've seen for the roost area across the road. This week, when I watched the area, again these birds arrived almost precisely with each other - spaced inches and fractions of a second apart. Last night they all went inside the hole in the big Valley Oak, then 2 came out, mounted briefly, then returned to the hole, stayed in/near it for several minutes, followed by a virtual instantaneous exodus of all 4 birds for the nearby hole in the Blue Oak, where they all (more casually) went in and where I caught them this morning. Last year, this "tight" flocking behavior was seen during The Song at Blue Oak and Arnold 3 in the Spring.