Great analysis. Its always good to have some prime feeding areas in your ‘birding arsenal’. It certainly makes “slow days” much more interesting. I imagine HMF benefits quite a bit from that kind of local movement. In fact, I think I can specifically remember times last winter where we had massive fall-outs of white-crowned sparrows (at Duke Farms) one day and you’d be inundated with a bunch the next. Probably individuals moving out of our marginal WCSP habitat and into greener pastures.
I did a little follow-up on my blog, discussing some of the common attributes that may make up prime foraging habitat: http://www.isoetes.blogspot.com

Duke Farms behaved like a good migrant trap on this day of S winds….only birds of interest were one black-and-white and a singing willow flycatcher

cheers,
Brian