We had explained the problem here several times now, and it still hold true here: We don't. Care about. Accurate zoology. Yes, a pigeon and a dove are biologically essentially the same thing, but very few people actually care about that on an imageboard site. The only thing that matters is that people can actually search for it.
The dove tag is not for realistic doves. It is for the common depiction in media (like anime) to portray a dove as a white bird. They are visually distinct and separate concepts, and we follow "tag what you see", not "tag what is most biologically accurate". And like it or not, but pigeons and doves are very much not the same thing, on a "tag what you see" principle. We don't need "white dove" as a tag, that's just incredibly redundant (and got pointed out as such in forum #266321). We just need a simple dove tag for white birds with a pigeon shape.
Also, did you think about searchability for the average user? Because your proposed set-up sounds like a complete pain in the ass to use compared to the current system of how we tag doves and pigeons. Not that this BUR would work, considering you can't mass update an already aliased away tag like "white dove", I don't think, but I still would like to know how you could ever expect the average person with limited bird knowledge how they could know and expect to use this set-up.