With larger casts, we were always able to get a birthday fund for cakes and cards (which, I might add, are much cheaper and can easily be passed around backstage). In smaller casts, the company always paid for it, and whether we got a cake for the month or individual ones depended on the # of bdays and the length of the run. Of course, I always got birthdays in my emergency info sheet, so I had the master calendar by the first week of reh and could let the office know so they could decide if they wanted to handle it - always gave them first refusal cuz hey, if they want to pay for it, I am happy to let them!