Rare twin giraffes were born this month at a nature preserve in Texas, marking only the second time that living twin giraffes have been born in the United States, the preserve said on Wednesday.
The babies were born on May 10 at the Natural Bridge Wildlife Ranch outside of New Braunfels, but the announcement was delayed because twins often do not survive, said Tiffany Soechting, the ranch's marketing director.
The giraffes - a female named Wasswa and a male named Nakato - are the only living twin giraffes in the United States, she said.
"This is an extreme honor," Soechting said. "There is a lot of pressure involved making sure mother and babies are healthy."
The twins are reticulated giraffes, a subspecies of giraffe common in zoos and characterized by large brown spots separated by white lines.
Wasswa was born first at 95 pounds (43 kg) and was 4.5 feet(1.37 meters) tall, Soechting said. Nakato weighed 125 pounds (57 kg) and was 5.5 feet (1.67 meters) tall at birth. In the East African language of Luganda, Wasswa and Nakato mean the first- and second-born twins.
Three-quarters of twin giraffe pregnancies abort early in the 15-month gestation or are stillborn, according to the ranch, which is 30 miles (48 kg) north of San Antonio. It bills itself as an "African Safari, Texas Style," where visitors can drive past free-ranging zebras, antelopes and giraffes.
Just nine sets of twins have ever been born alive at zoos worldwide, said Laurie Bingaman Lackey, who keeps statistics on giraffes for the Association of Zoos and Aquariums. That's out of more than 8,000 recorded giraffe births in zoos worldwide since the 1820s.
"The twinning rate in humans is one in 80 pregnancies," Lackey said. "The twinning rate in giraffes is one in every 280,000, and keep in mind there are a whole lot more people in the world than there are giraffes in the zoos of the world."
The twins' mother, Carol, who was also born at the ranch, is doing well, said Kenny Patin, the ranch veterinarian.
Being born is rough for giraffes, Patin said. Mothers give birth standing up, requiring the newborns to fall six feet (1.83 meters) to the ground.
Babies are generally standing and running around within an hour of birth, but Nakato failed to stand, and his birth was made more complicated by thunderstorms moving into the area, requiring that he be bottle-fed and moved to a special area for care.
Nakato has since been returned to his mother and sister, but Soechting said that Carol saw him as a threat and their relationship remains unclear.
"The twins and the mother may be able to co-exist in the same enclosure, but as the births are so rare, science is not able to define what can be expected," she said.