January -
February - 1
March -
April - 2
May - 1
June -
July - 1
August -
September -
October -
November - 2
December - 2

Shadow - April 2nd
Micki and Mini - November 24th
Jack - December 16th
Kyra - July 11th

Edit: Aww! I just realized that Ki and Shadow have the same birthday!