I suggest you try my application Dates to iCal.
Dates to iCal 2 is a replacement for Apple's birthday calendar for iCal. It has a range of features to allow the user to choose what, and what not, to sync to iCal from Address Book. As well as automatically syncing birthday dates from Address Book, Dates to iCal 2 can sync anniversary and custom dates. It can set up to five alarms for each date in iCal and can also set different alarms for birthdays and anniversaries. It allows the option of only syncing from one Address Book group.
It is shareware, you can try it for free 2 weeks before needing a £4 registration code.
As I sell software on my site and ask for donations, the Apple Support Communities Use Agreementrequires that I state that I may receive some form of compensation, financial or otherwise, from my recommendation or link.
I had a similar problem - here's how I fixed it moments ago:
Go to settings --> facebook --> and turn off contacts and calendars and click "update contacts." This will remove the facebook events from your calendar as well as your contacts. Now you can turn contact sync back on, update contacts, and you will get your contacts WITHOUT all of their birthdays.
Note: I performed this just a few min ago, and after hitting update contacts, the bar went very quickly and said that 0 contacts were updated. This is false, and as I type this message, my FB contacts are getting sync'd.
Goodluck, hope this works for (all) you too!
I too am wanting to delete the facebook birthdays from my ical, but I currently now have my facebook birthdays showing up twice on each day?? You mentioned about going to settings ---- facebook ---- turn off contacts etc, but I cannot find a settings option in my ical, and under the settings in facebook, there is no option like this? Could you possibly post a screenshot to show me or talk me through in an idiots guide?
Hope you can help!