How can I create a birthday calendar using the Date and Calendar modules?
You can try with Birthdays module. It allows users to add their birthday to their profile.


  The Birthdays module allows users to add their birthday to their profile. It also lists birthdays on a seperate page and in different blocks. Users can receive an e-mail on their birthday automatically, and the administrator can receive periodic reminders of who are having their birthday. Uses Profile module from core.