I've never tagged a hummer but they visit so often the air would be full of them if a totally different bird each time. They are quite territorial, and one will stake out a feeder, then will often defend it against all comers.

1:1 is way too sweet, so Audobon society claims...they say this is actually not good for the birds, way over the top compared with their natural nectar foods...1:4 more closely approximates that.

Also, if you are finding solids in the hummer juice, it's likely because the sugar was not fully dissolved...it takes a couple of minutes at simmer, with attentive stirring, to make sure of total dispersal. Fussy, fussy! But they are well worth the trouble!