Thanks Rodrigo and mayoayo!
Rodrigo - I'm definitely going to do more with markers, as I also like how they turned out. The last few I've been doing are 'quick and dirty' with watercolor pencil and water brush since I'm still in catch up mode to sketch the species I've seen so far this year. The pencils and water brush are quick but don't give the best results. But of course, they're only sketches...and I have to keep telling myself that sketches aren't done with the purpose of making a finished product.