I have a Conure (parrot type bird...) and read that they absolutely WILL NOT eat anything their parents didn't show them was edible. Considering I bought her at 6 weeks... from a breeder... that would have been tough, but now that she thinks I am her mommy, she will eat it if I either nibble it first, or put it between my lips to feed to her.
Now to chickens... I have 4 six month old RIR's, and they would not even look at the bucket of snails I hunted diligently for, one night! Worms? Heck NO... obviously poison!
I also now have a batch of 8 week olds, and I taught them to eat worms etc early. Then, when I moved them out next to the big girls, It was a MIRACLE!!... when the big girls saw the little girls were getting treats, they changed their minds and started munching!
My girls also like white food especially... maybe it is the contrast. Not thrilled with pasta, or pumpkin, but will kill for pomegranets, lettuce and wild mallow weeds.