Now there’s a tough nut to crack: A squirrel finds a perch on a knot high on a tree in our woods and takes a crack at opening a black walnut. Nov. 11, 2017. Nikon D500, Tamron 150-600mm G1 lens, f/6.3, 1/250th sec., ISO 1131, VR on, 600mm (900mm FX). ©2017 John M. Hudson