Not with Botulism - it is fortunately rare. If your mulch pile is aerated properly (turned over regularly) then the botulism bacteria would be less likely to grow. We hear reports up here of water birds dying from botulism that grows in algal blooms and then the toxins are ingested by the birds - sometimes there will be dead ducks strewn on beaches.
Aflatoxins I have seen, not in birds but in dogs that got into garbage. Oral activated charcoal products will bind the toxin in the digestive tract and allow it to be passed, but I have not used them in chickens. This website does talk about using activated charcoal the the dose used in chickens -
http://gardentenders.com/members/XploreOrganics/blog/40
Aflatoxins I have seen, not in birds but in dogs that got into garbage. Oral activated charcoal products will bind the toxin in the digestive tract and allow it to be passed, but I have not used them in chickens. This website does talk about using activated charcoal the the dose used in chickens -
http://gardentenders.com/members/XploreOrganics/blog/40