This grey squirrell was under the apple tree in my garden - an easy target for a 300mm lens I took 6 photographs and based this drawing on one of them.
I've used Wollf Carbon Pencils - Artifolk sell them in sets of B, 2B, 4B, 6B and they make rich black marks. They don't go shiny like graphite when applied thickly. I was taught a very traditional technique in the Life Room - tones built up gently and gradually with hachures. It's a lovely way of drawing