Question: Is a bird who keeps flying back with money from unknown source(s) to his caregiver held in his beak considered as stealing?
Answer: Although some might deludedly ‘rejoice’ in having this ‘wealth-giving bird’, unless the source(s) known prove otherwise, this is most probably breaking of the Second Precept against stealing. The caregiver is also culpable for not discouraging this, thus with both creating evil karma. Having such a bird does not spell the end of financial worries; but the beginning of moral concerns.
The caregiver should educate the bird to not do what he does, and reject any more probably ill-gotten gains. Even if what stolen is donated to charity, it might still be stolen. Thus, the potential stealing must stop. And if the source(s) of the money accumulated so far are unverifiable after reasonable investigation and time, it should be donated entirely, to return it to society, for its betterment.