these tutorials are always way too advanced for the average person, way too advanced. to draw an owl that well takes daily practice for hours and hours, over months and months believe me. People and animals are the toughest subject matter to conquer, and no book will get you to that standard without you knowing all the fundamentals of art first. You will need to study animal anatomy to be able to draw any animal in any pose, from any angle. The proportions alone will not be enough. Imagine trying to draw that owl from above, or behind, and then drawing it again with it's wings spread out and a rat in it's mouth. Don't get frustrated trying to draw this stuff until you can draw basic shapes in perspective, from any angle. Once your brain starts to picture everything in 3d, you will be able to tackle these kinds of images. Even if you keep copying this image, you will be very limited as you won't be able to draw 'on demand', as you will need to really understand how an owls anatomy works. It really really does take time this stuff, lots of time and lots and lots of errors on the way.