Winter Treasure LbNA #19906

If you'd like to hunt for treasure this year
There's a box planted in Gardner, I hear
It's found in a sanctuary, small and serene
Not far from a college on a street that's green
Just look for the birds (like robins and doves)
Go right on the street everybody loves
Follow straight to the end, then park in the lot
Please donate some money to enjoy this spot.
If you'd like to hike (fine), or snowshoe (that's grand!)
But unfortunately rules say no skiing this land :(
Find your place at the sign, head straight down the slope
Choose to head left or right (you chose left, I hope)
With the pond on your right, and on the left brush
The path enters the woods (look out for that thrush!)
Stone wall on the left, stone wall on the right
Travel softly in winter and you may see a sight!
Keep going until a tree once barred your path
Sidetrack to the left, now it's time for some math!
Place your feet at the fallen tree's base
Walk the bearing 160o, with 13 the pace
Stop! Look ahead to your left!
Do you see a big rock, that a glacier has cleft?
The land slopes on your right, but walk on the edge

Note 2/17/14: Last reported find in August 2013, still there (and still annoying geocachers).
Head to that rock, but please mind the ledge
Now turn and look all around
Under some very large logs on the ground
Did you find the treasure you seek?
If so, please rehide, so you can't sneak a peek!