*trying to make it a bit easier for you to update* I'm not sure about the names so I left those out but I still hope it helps a bit when you don't have to search for the pictures etc. on your own ^^" This are all bunnies released in 2011.
Chinese New Year
All 3 Uncommon
Easter
Adoptable for free [Adoption Limit: 15] on 18 April (not sure about the following days)
All 10 Uncommon
Adoptable for free [Adoption Limit: 10] on 23rd April (not sure about the following days)
All 6 Uncommon
Traded in for Egg Tokens
First one Uncommon -- the other 11 are all Rare
Halloween
Adoptable for free on 31th of December (not sure about the following days)