You can contact your targeted lists by birthday using the "Birthdays" output options in Targeting.  After selecting your target of voters, choose a date range of birthdays to export or print labels for.  The labels report will print the labels in ascending order of date so you can send your mailers each day to time delivery appropriately.

You can also add the voters to a Phone Project to make phone calls each birthday.  When the "Only Queue Birthdays" option is set on the phone project, the queue to be called will only be set to those voters in the project who have a birthday that day.  To access this special setting, the name of the project must include "Birthday".