I've a thing for realistic animal drawings: I find them relaxing in a certain way. 
Below, there are traditional ones and digital sketch in black and white.

-Red eye tree frog (Agalychnis callidryas) lives in the central America. (acrylic ink)

Falena Cecropia: another american beauty.  In this page I've illustrated their life circle(acrylic ink)

And yes,I'm in love with big cats. (digital drawings)