Good common small breed would be birmingham rollers (easiest cheapest n do good crowding in small cage/coop eating half to fourth of other pigeons at half to fourth of cup for two). Only two drawback having flying rollers is most have great flying n performance except in standard ones, ten to thirty feet of not able to count backwards Summersaults straight down. No twizzling flitting etc even.. Good rollers can be gotten for free, or two to five dollars, but usually start at ten dollars and go up by foot or more, but usual rule of thumb "never pay more for bird than ten dollars, as its still just a bird"! Lol ol hobby guys say.
I keep Portuguese tumblers that are budgie/parakeet sized though too (fourth to half size of other pigeons). Lol. I have Portuguese tumblers tumblers for sale at $20 a pair (usually at very least $25-$50), as are rare getting performance type (well any that perform or fly and standard of breeding only to n for smallest while conforming to structure of birds), that are show quality also, and some banded still, as had bands of some cut off by shower when he sold to me.
Owls are short faced small pigeons in class that usually have interesting showy feather mutations like frizzling or frilling like my Chinese and Italian owls I had.
