First, I am with Mike, I save everything a couple of times. I have a LOT of pictures to store but storing in more then one area is very good and I always keep my originals.
As for the cropping question, here are some things to consider:
1. Photography is an art to be used by the photographer to accomplish the purpose of the photographer.
2. All tools of photography can be used at the photographers will to accomplish the above purpose.
3. All “rules and guidelines” are centered on the “average viewer’s perception” shall we say as to what they expect.
4. All rules and guidelines can be broken to accomplish the purpose of the photographer!!
With all of that said, what is the purpose of your photo? Quick thoughts:
Identification of a bird? Then crop in the best ratio that keeps your picture quality as clean as possible with the photo taken, so ID can be as easily made as the picture can offer.
Portrait? Learn things like rule of thirds, letting the bird look or “move” into some space in the picture, de-clutter background, find leading lines that bring the eye to the subject, get the bird to pop in the picture in such a way that it grabs the viewer’s attention and crop accordingly.
One last thought, I do try to get the best composition I possibly can in all my photos but let’s be honest, wildlife has never read a book or taken a course on posing and modeling. We as viewers make up what we believe is “beautiful”. Yet the truth is, practicing, learning to get closer without disturbing our subject, and learning to use our equipment to the best of our abilities, allows us to crop lightly leaving us with great pictures. Yet sometimes, wildlife does not let us get close. Then my cropping is based as well on the quality of the picture.
I will attach a couple of pictures showing before and after pictures. Remember, I like to shoot photos that I can hang on the wall. Not a high success rate but that is my purpose.