I love nothing more than stories of unlikely animals becoming friends, like in the classic Disney movie The Fox and the Hound. It's even better when these stories happen in real life. Even more amazing than when two animals of different species become friends, is when animal mothers adopt a needy baby of a different species. Its unlikely for animals to even adopt a non-related animal of the same species. Can anything be more heartwarming, than a story a lion caring for an orphaned baby antelope, an animal a lion would usually make dinner? These stories really prove that animals can be just as compassionate and generous as humans.
Two baby Sumatran orangutans and two baby Sumatran tigers become great friends after all four are abandoned by their mothers.
Owen and Mzee are perhaps the most famous story of cross species adoption. Owen, the baby hippo who got separated from his family in the 2004 Tsunami, chose to make Mzee the 130 year old Aldabra tortoise his new mom. It took a little convincing but Mzee soon accepted Owen and the two have been insperable ever since.
Koko the gorilla and her adopted kitten.
There is also a great story and video about a baboon who adopts an injured chicken.