As long as the pigeons are not free range birds they should be fine. The reason I say this is that pigeons carry more diseases then wild rats and more often then not are carrying pests. A free range bird is also not a picky eater and can ingest something that can harm your snake(s).
Also from what I've heard and experienced some Retics once they change to birds they have a tendency to not change back to a rodent. Then you could end up being stuck trying to find chickens or something when they're out of season.
Hope this helps. 
Oh and if you can find guinea pigs they're usually pretty cheap and have more meat on their bones then a bird. 
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Christine
Tails With Scales Reptiles
www.tailswithscales.com
Looks, brains, and venom . . . . how do I stay single?