So, in line with my comparison of text between the new Crossley ID guide and recent field guides, here's a comparison chart showing number of birds illustrated for the same species:
Again, note how Crossley ID stacks up to the others.
103 Big Sibley
84 Crossley ID
37 National Geographic
Again, note how well Big Sibley does in comparison. Book jacket claims 6,600 in Big Sibley, compared to 10,000 images claimed for Crossley ID (and 3400 photos in Stokes). As a direct comparison, many of the Crossley ID images are small and distant birds, especially distant flocks of birds--which is useful in itself, but not always the same way as illustrations showing additional variations.
I'm also impressed with how well Kaufman stands up, compared to the others in the middle of the pack--very respectable for such a trim guide (and he manages to show a juvenile Saw-whet Owl, which even Crossley ID doesn't pull off)!
So that's how the numbers stand in this comparison. But there are probably even more than 10,000 birds in Crossley ID--just check out his shot of the Black-legged Kittiwake colony, and it's anyone's guess how many birds are in there! For the record, here's the number of illustrations claimed for these guides:
10,000 Crossley ID (combined photos--who knows how many birds that really is!)
6,600+ Big Sibley (illustrations)
4,000+ National Geographic (paintings)
3,400 Stokes (photos--some are of more than one bird)
2,000+ Kaufman (photos)