I'll copy the directions I got from Cliff C. last year:
To get to the Pine Hill area you drive down Pine Hill Street in
Lancaster, which is on the north side of Rt 117 west of Bolton Flats. Go down the street to the end where it is gated off at private property. To the left is a spur with another gate and this is the entrance to Pine Hill.
You can park off to the side on that spur with the gate & entrance, there's usually a couple people parked there. The walking is pretty easy; it's flat and unpaved. When you first enter, for the first 100 yards there's a bit of a deciduous/conifer mix and the couple times I've gone it's been swamped with a dozen species of song birds; always a great way to start a trip. Past that you enter the sandy/flats area. There are prairie warblers everywhere as you walk along, I see/hear more there than the rest of the year combined and doubled probably. The further down you go, until you reach about the middle, the more likely you are to find grasshopper sparrows. I've had better luck looking to the right of the road. There's a field on private property out on that side, and there's fence posts. If you observe those posts for a while you're bound to see a couple grasshopper sparrows. They seem to gravitate to the posts with the 'Posted - No Trespassing' signs on them. The sparrows have no moral compunction and trespass as they see fit. The vespers are a bit more random, but will come up and sing from the tiny spruce trees on occassion. Most of the time though they seem to skulk and sing from more surreptitious spots. I had really good luck down the far end of the reservation this recent trip, a couple were singing.
Field sparrows are found throughout the whole area as well, again I've had more luck at the far end of the reservation finding them. If you enjoy towhees you'll also be in luck, you'll be force-fed tea for the whole trip. Indigo buntings are around, although this last time I think they were paired off, I saw two VERY briefly at the start, and never heard the male sing.
There's also woodlands up behind that have a lot of trails, if you follow them down far enough you'll hit a river. It's pretty reliable for pine warblers, several thrush species, waxwings, and a couple other warbler types. The crossbills were more happenstance; 3 minutes earlier or later and I would've missed them....still, they're around apparently.
Hope this helps
Matt S
Newton, MA