Great question.

Every photo starts out with one 3-star rating. This is to prevent a single vote for a new photo to propel it instantly to the top or bottom of the pile. If no one ever rates it that’s how it stays. When we review and accept photos we are checking for identification accuracy. Currently we don’t rate photos but perhaps we should.

Many photos, especially newer ones, have no additional ratings. We encourage photographers to rate their own photos as a way of helping them and us (and other users) focus on the better photos. We would appreciate it if you give your own ratings, especially when you see things that are out of whack.

Our purpose for rating photos is to help differentiate those that might be more useful to other people from the less ideal shots. We have not defined a rating system, but usually recommend something along these lines:
1 = hardly identifiable / subject barely visible. 1-stars are really poor shots, useful as a “photo lifer” but otherwise not likely to be of interest to anyone besides the photographer.
2 = perhaps useful in the apps if no other photos are available. Out of focus, very poor lighting, and/or the bird is very small in the frame.
3 = an ok photo, but there are flaws. For example: the object of the photo is somewhat obscured, the object fills only a small portion of the frame, the lighting is bad, the focus is off etc.
4 = a good photo with no real defects, but lacking what it takes to be 5-star. In focus and the subject more-or-less fills the frame. Good lighting. A very helpful photo for a birder in the field. Perhaps the background is a bit too busy to be a 5-star.
5 = like 4, but with that extra spark that makes it art quality. Great composition and lighting plus an interesting photo.

Photos that are rated 4-stars or higher are considered "great photos" which you will see on your photographer page.