The main ingredient in most bead release is the same as (or very similar to) ceramic kiln wash. Depending on what brand of release you are using, it will certainly contain other ingredients, possibly including graphite and other substances. To research the potential toxicity of a substance, you can google the MSDS (material safety data sheet) of that material. For instance, here's a link to the MSDS for ceramic kiln wash:
http://www.lagunaclay.com/msds/pdf/5refract/rf504.pdf
You could also contact the manufacturer of the bead release you are using and ask them for an MSDS (they probably will refuse on the basis of it being a proprietary formula), or just ask them your original question, or ask them if they are adding anything that might be toxic to birds...
Good luck, and make sure you come back and tell us what you find out!