I would like to learn to identify gulls by starting with the most frequently occurring gulls.
For instance, suppose about 50 percent of the gulls in my area (Gdansk, Poland, as it happens) were species X. Then that's the species I would want to learn first. Learn that species and I would be able to identify half of the gulls I was likely to see.
If another 25 percent in the area were species Y, then that's the one I want to learn next, and I would want to focus on differentiating X from Y, and not worry about the rest of the birds yet.
From that point, I would fairly reliably be able to identify about 75 percent of the gulls in the area. (The odds of my knowing the identity of the next gull I saw would be about three in four.) The reliability of my identifications would improve with each species I learned, but each additional bird would give me diminishing returns in terms of being able to identify the next gull I saw. If just 1 or 2 percent of the birds I was likely to see were species Z, I might not even bother to learn about species Z, not at first.
Something like that. I don't know if I'm making myself clear. I hope so.
Is it possible to find data that would help me with this? Population estimates that would let me decide the approximate odds of the next gull being species X or Y or Z? Not just "The most common gulls in area A are X, Y, and Z" but "In area A, about 20 percent of the gulls are X, 10 percent are Y, ..."