Regarding fabric and birds ...
Another reason not to give fabric scraps to birds is that they'll re-arrange the scraps over and over when they build their nests, and in the process, some of the strings will fray. The frayed strings can easily get tangled around the birds' legs, especially small birds, whose legs are the size of toothpicks. I used to have finches, and found this out the hard way. Thankfully I found the bird in time and untangled her leg. Whew! Had I not found the problem, the thread could have cut the circulation off, and her leg and foot would have died. Birds can be so fragile, especially tiny ones who don't have enough strength to break the thread and get it off their leg.
Personally, I wouldn't chance it, but if you do decide to let the birds have the scraps, cut them into 1" or smaller bits to help eliminate the possibility of threads getting tangled around their legs.
