If someone is truly your friend, more than likely you already have a birthday notification for them in iCal. Luckily, getting rid of Facebook’s birthday notifications in iCal is a quick and easy task. Here’s what you need to do:
Open the iCal application.
If you can’t see your calendars listed in the left hand column, click on the “Calendars” button at the top left corner to display them.
Look under the “Subscriptions” section of your calendars. You should see a Birthdays calendar there.
Uncheck the Birthdays calendar to disable it. You will see all of the birthdays on your calendar disappear.
You’re now Facebook birthday free – no more notifications! Alternately, you can go through each birthday individually and delete the ones that you don’t want to be notified about. This will be time consuming (especially if you have a lot of friends), but it will be useful if there are certain friends whose birthdays you don’t want to miss.