The baby owls I made from a template/tutorial at Hobby di Stoffa. The tutorial (LINK) is in Italian, but the pictures make it very easy to follow. I didn't print the owls full size -- they are 70% scale, FYI.
For the mama owl, I found this great tutorial (LINK) on the Sew Little Fabric blog. PLEASE NOTE: I changed the design of the owl a bit: I made the wings larger and DID NOT fully sew them to the body. I added a small Velcro patch as well, so that the mama owl could hold her owlets like in the book. You're welcome to my PDF of the altered wing design (LINK.)