A three-year-old giraffe and Wilma, an ostrich, share a moment at Busch Gardens in Tampa Bay, Florida's 65-acre Serengeti Plain Aug. 1, 2009. The animals usually hang out with their own species, but zookeepers say the unlikely pair can't seem to get enough of one another. Matt Marriott/Busch Gardens/AP
Bella, a stray dog, has become best friends with Tarra the elephant at The Elephant Sanctuary in Hohenwald, Tenn., March 20, 2006. They follow each other everywhere and even sleep together. Melanie Stetson Freeman/Staff
Baby, a French bulldog, befriended six wild boar piglets at the Lehnitz animal sanctuary outside Berlin Feb. 15, 2012. Baby started snuggling with the piglets, which are about her size, when they arrived at three days old shivering from cold. The piglets' mother was likely killed by a hunter and the litter was found abandoned in a forest. The piglets are being bottle fed. Michael Sohn/AP
The late artist and wildlife photographer Jane Burton made this image of a kitten snuggling up to a rabbit in Birmingham, England. Jane Burton/Newscom/File
Pinky the Pig poses with a kitten on her head in Watford, England. Arthur Sidey/Newscom/File
A squirrel monkey rides a blue and gold macaw in San Agustin, Colombia. Alejandro Jaramillo/Solent News/Splash News/Newscom/File
There seems to be true friendship between Ravi the Bengal tiger and Duke the German shepherd in Watford, England. Gavin Kent/Newscom/File
Baloo the bear puts his paw around Bengal tiger Shere Khan at Noah's Ark zoo in Locust Grove, Ga., observed by an unidentified man. Wenn.com/Newscom/File
A kitten makes friends with a duckling in Watford, England. Sidey Arthur/Newscom/File
This kitten looks perfectly at ease in the arms of a chimpanzee. Index Stock Imagery/Newscom
A dog nurses kittens in Beijing. Since the kittens' mother died, the dog has been their surrogate mother. Zhu Jialei/JHSB/ChinaFotoPress/Newscom/File
Datvi the bear bonds with sheepdog Pars in Rize, Turkey, as documentary film producer Cemal Gurlas looks on. Mr. Gurlas took over the care of Datvi when her mother was killed by hunters. IHA/UPPA/Photoshot/Newscom/File
An orphaned deer and a baby bobcat became best friends after a devastating forest fire killed their parents in Santa Barbara, Calif. ZUMA/Newscom/File
After being rejected by its mother, a fawn was rescued by a dance teacher and became friends with her two German shepherd dogs in Hamburg, Germany.
Gibbons are jungle divas. The small apes use the same technique to project their songs through the forests of southeast Asia as top sopranos singing at the New York Metropolitan Opera or La Scala in Milan.