Start by working up several pages of gestures on each animal using vine and compressed charcoal
on a light weight paper. Fill the pages from many different vantage points until you feel comfortable that you have a general understanding of the form and movement. Transition from line to value within each drawing by alternating from the side of the charcoal stick to the point and back again. Think thick/thin lines and value, but work very quickly; always remembering to look at your subject as often as your sheet of paper. Mix up the marks
by breaking off different lengths of charcoal stick.