From National Geographic News comes this interesting story:
The strength of a unique male bond between a young hippopotamus and a 130-year-old tortoise will be tested later this spring when conservation workers introduce a female hippo to the mix.
The pending introduction serves as an intriguing plot twist to the unlikely story of a hippo and tortoise brought together at Haller Park wildlife sanctuary in Mombasa, Kenya, in the wake of the December 26, 2004, Indian Ocean tsunami.
The conservationists hope the two hippos will bond with no objection from the tortoise, named Mzee. Such an outcome will allow Mzee's return to the safety of his original enclosure.
While other tortoises, monkeys, and antelope roam in that enclosure, Mzee has shown no affection toward any of them. But he has surprisingly become attached to the young hippo, Owen.
"He will grow to anywhere between three and four tons—he's gonna be a big male hippopotamus," said Paula Kahumbu, the general manager of Lafarge Ecosystems, the Kenyan environmental restoration firm that manages the wildlife sanctuary.
"He's already quite playful, already quite strong," she said. "He could injure Mzee at any moment. He's very childlike in his behavior. As he gets older he will get rougher. Mzee is not a flexible animal—he could be injured."
But how Mzee and Owen will react to the presence of Cleo, the female hippo, and a subsequent separation is unknown, Kahumbu said. If one cannot live without the other, some sort of accommodations will be made.
The really fascniating part:
Nevertheless, Mzee follows Owen around, nudges him to go for walks, initiates play in the water, and even stretches his neck out so Owen can give him a lick.
There has been growing evidence of physical communication between the pair, with Owen nibbling Mzee's back feet to get him to walk in a desired direction. The two have even developed a sort of vocal communication of their own, Kahumbu said.
The vocalizations are not the honking of hippos or the grunts and hisses of tortoises, but rather a soft whimpering that emanates from one and is mimicked by the other.
"It's very high pitched; definitely not a stomach sound, as some had suggested," Kahumbu said. "They're vocalizing towards each other."
What the animals are trying to communicate is not yet understood, but researchers think it is a contact call made to get the other's attention.