After Spending a lot of time alone in the same room of the owners house, they grew fond of each other. The crow is almost always on the dog’s back, the dog even barks when people try to touch his pal. The owner built a custom harness for more comfortable rides. 
A black swan feeding fish at a public park.
After a devastating forest fire, fire rescue ran out of crates for the animals saved from the blazes. This fawn and baby bobcat were placed together in the office. Hours later, firemen noticed they’d taken a liking to one another and cuddled for the duration they were kept together.
A duck and house cat raised together by a family. Supposedly the duck hates water and hasn’t figured out yet that it can fly.
This macaque and dove lived together in an animal protection center off the coast of China. They ate, played, and slept together for two months before being released into the wild.
A wild life park in China adopted two tiger cubs, which were soon adopted by a worker’s dog that happened to be in the pen frequently.
The Fernandez family adopted a tiger cub after he lost his family. He’s been raised with the family dog since youth and they are inseparable.
A five week old boar plays with Candy, the jack Russell terrier in Ehringhausen, Germany.
Humphrey was a house pet that became too large and was moved to the Rhino and Lion Nature Reserve in South Africa, where he was safe but lonely. Cameroon Pygmy Mountain Goat climbed Humphrey’s enclosure fence and befriended him.
Sobe the iguana and Johann the cat were both rescued by a woman in Brooklyn, NY. Every day when the iguana is let out of her cage, she seeks out Johann for play time, along with a rabbit also kept as a pet.
A baby hippo was swept away by a tsunami and rescued by a wild life reservation. A 130 year old tortoise immediately befriended him.
Everyone knows who Koko the gorilla that speaks sign language is. For her birthday one year, she signed to her teacher that she wanted a kitten. Koko’s teacher wasn’t surprised, as Koko’s two favorite books were about cats. They adopted one from an abandoned litter and Koko showed it tender care and gentleness.
A lioness abandoned by her pack decides to adopted a baby impala after killing its mother. Several times, she tried to leave the baby in the company of other impalas, but ended up having to take the baby back under her wing after the adult impalas were frightened away by her
A lion, tiger, and bear raised together in the same enclosure at Noah’s Ark Sanctuary in GA play ball, cuddle, and chase each other.
A giraffe and ostrich form an odd friendship at Busch Garden’s in Florida.
A baby impala was left behind after the rest of its group ran away from the cheetahs. Instead of preying on the impala, they played gently with it a bit before simply getting bored and leaving it.
Owls that hatched at a hawk conservatory were adopted by the park keeper and became friends with his pet dog.
After a family took in this stray cat, she grew fond of their elderly dog. Realizing the dog was blind, the cat took on the responsibility of leading the dog to his water, food, shade, and toys. She would follow closely under his chin to guide him.
A stray cat wandered into this asiastic bear’s enclosure at the Berlin Zoo. It’s been coming back frequently for 10 years to visit its friend.
This pair have been seen together for over a year in Lake Van, Turkey. They were first spotted by local fisherman who witnessed them sharing a fish and playing together.
At the TIGERS institute in South Carolina, a chimp raises tiger cubs after they were separated from their mother.
A photographer witnessed a wild polar bear coming upon tethered sled dogs in the wilderness of Canada’s Hudson Bay. Instead of devouring the dogs, they played and cuddled. The polar bear returned every night that week.
Other examples of strange and improbably animal friendships:
