I recently bought Martin Sailbury's book "Illustrating Children's Books" (which is highly recomended by the way). In one chapter about drawing animals, he suggests drawing chickens because of their interesting shapes and "stacatto movements". Coincidentally, my dad recently bought six chickens so I went out drawing them!
All the observational drawing was very good practice for transforming prepartory sketches into my finished drawings. I've already come up with a picture book story, which this is a concept drawing for: