Interesting observations re food preferences among your yard birds. I put out seeds & suet (& peanuts for the jays) in my backyard but little or no bread (mainly because bread tends to get eaten up in my house with no leftover scraps). Maybe I'll start putting some out to see how the quail, towhees, House Finches, House Sparrows, Mourning Doves & the rest react.
As I've suggested in a previous thread, I think a lot of "anti-bread" propaganda is motivated by a hidden agenda on the part of people who object in general to the feeding of waterfowl & other birds in public spaces, not because it's "bad" for these creatures, but for various human reasons--they don't like the mess, or they're concerned about "hygiene", or simply because they're unenthusiastic about walking through packs of large aggressive birds scrabbling for food.
This, of course, is in no way to impugn the motives behind the Surrey "bread amnesty" which I'm sure are completely sincere & above-board. But, I'm still curious to know, is bread bad for ducks?