I was walking my dog down west on Birchcliff Parkway at 4:34pm EST when I came upon a large group of hundreds of crows streaming from north to south in a flight path roughly across the Champlain Chocolates parking lot. I had intentionally picked this time to go for the walk as I had seen another steam in the neighborhood a week before at roughly the same time (actually, more like 50 minutes earlier). Aside from recognizing their silhouettes in the sky (see pic), I also heard enough tell-tale cawing to make me believe these were indeed American Crows that we were seeing.

Follow-up: A few minutes later, we walked north on adjoining Cherry Street, and, as we rounded the corner (the street turns east), I saw another large group of crows --not as many as this group, I'd estimate closer to 50-100-- flying north from the south. It appeared as though they were flying into next-door Calahan Park, although they could have easily kept flying over the park for all I was able to discern due to the houses & trees blocking my view.

At any rate, I thought this an interesting observation, as it implied that the south-bound stream I'd seen at 4:34 wasn't going in a "canonical" direction, and either part of it or maybe a completely different group were going in roughly the opposite direction. Obviously, Calahan Park bears further investigation around dusk!