Cheers chaps.
Honestly, the standard of recent postings on BF have left me breathless and envious in equal measure! So much so that I once again start thinking 'how is this so good' followed by the cardinal sin of comparing it to what I try to do!
Apart from the lack of colour - one day, probably when the Needletail flys through my patch - I really would welcome any form of constructive criticism relevant to drawing whether it be about perspective, fore-shortening, value, tone, over-working or strive to keep it simple - whatever. Spending hours wondering if I'm doing the right thing in a world of DSLR's, inspiration and guidance are only to be found on BF. Don't be afraid - if you can just say 'I would have done it this way......'
It's hard to give an answer to these generalized questions, Russ, though since I've said this I'm sure someone will! My personal feeling is that you have a great sense of the shape of the bird, and really concentrate on getting that right. That's the best place to start - with what you already have a solid foundation in.
All the other things are just art jargon that may or may not be helpful. My feeling as both artist and one-time teacher is that those things, e.g. perspective, only become truly important when you realize that you're making a mess of them. At that point you then have the motivation to learn how to do it correctly. But I personally wouldn't worry about them until you find something lacking in your own work. Then try to figure out what it is and go from there.
I do see some similarity between your work and that of Alan. Maybe by comparing the two you can see some aspect that you like in his or not in yours, or vice versa. I only mention Alan because I thought I saw some similarity when looking at his recent sketches. Maybe you won't at all but maybe you will with someone else. That to me is one way to start.
Another, and this is what I'd recommend, is to do your next work, for at least a week or so, in another medium. I know that this will be hard. As Colleen says about her recent plein air painting you feel like you're back to being a beginner. But you learn a lot by trying to do more or less the same thing in a new medium. It gives you additional perspective, no pun intended, on both media. So for instance if I were giving you a personal tutorial I'd say get out in the field with watercolors and a big fat brush. When I was a computer programmer, until a few months ago, I found that every time I tried to learn a new language I actually learned something new about my old languages. So all the knowledge just accumulates and reinforces itself, much like birding I guess.
This way you'd have to work in value and mass, not line. There's nothing inherently better about value and mass over line and shape. They just all go together and I think all of them make anyone a better artist.
As I said I don't in anyway mean this as a criticism. I think your current work is very strong as is. I'm just trying to think of the fastest way I can think of to progress. I could, as always, be completely wrong!! Hope this is helpful.