February 26, 2000
Two young zebras of an endangered species died at National Zoo facilities this winter, apparently because keepers failed to feed them enough fat and protein and keep them sufficiently warm during frigid nights, officials said yesterday.
One of the zebras, a 1-year-old male from the Detroit Zoo spending his first winter in the nation's capital, was discovered dead in his heated barn at the zoo Feb. 1 after a night when temperatures fell to 24 degrees.
The other zebra, an 8-year-old male with a history of medical problems, died Jan. 22 at the zoo's Front Royal Conservation and Research Center. He had been moved from the zoo more than a year ago and was to be shipped to another zoo.
National Zoo spokesman Robert Hoage said postmortem exams indicate that both animals died of the cold weather and had all but depleted their energy stores of fat. Pathologists are looking at whether preexisting medical conditions might have made them more susceptible to the cold, because two other young zebras at the zoo survived without health problems.
"The National Zoo is saddened by these losses and is determined to take whatever measures are necessary to prevent such deaths in the future," Hoage said. "This is a serious situation."
Both animals were Grevy's zebras, a solitary, grazing species native to the arid, bushy grasslands of East Africa. The striped creatures are listed as "threatened" on the endangered species list, because poachers who sold their hides sharply reduced the population during the 1970s. Only about 5,400 remain in the wild, and about 220 are in North American zoos.
The zebras are named for Jules Grevy, a French president who was given the animals by the king of Ethiopia. They live up to 18 years in the wilderness and as long as 30 years in captivity.
The National Zoo replaced its common zebras with Grevy's zebras in 1993, holding males of the species as part of a coordinated breeding plan. Zoo officials could not recall ever losing a zebra of either species to the Washington winter.
Hoage said the zoo's three newest zebras had a special barn for winter shelter that was equipped with long, electric heat panels that the animals could snuggle up against--and that were designed to keep the temperature inside at 50 degrees. But the temperature in the barn fell below 50, and one of the zebras died.
"We apparently overestimated the barn's capacity to hold heat," Hoage said. "We don't know exactly what the temperature was, but it got a lot colder than that."
He said it was unclear what went wrong at the barn in Front Royal, where the other zebra died, though zoo managers are examining whether a heat lamp malfunctioned and whether the animal had enough hay for bedding.
Nutrition may have been another factor in the deaths. The zebras were on a diet of limited fat and protein to prevent them from becoming overweight and suffering leg problems. But zoo managers may have gone too far, Hoage said, because tests showed the dead zebras had almost no stored fat.
The zoo has since added space heaters to the zebra barn and installed foam padding covered with six inches of hay in the stalls. The two surviving zebras will be locked in the stalls when the temperature falls below freezing, and a new furnace will be added to the barn next year, Hoage said. Zoo managers also have added protein and fat to the zebras' meals and will be acquiring scales to monitor their weight. Bruce Read, a curator at Disney's Animal Kingdom who formerly coordinated the North American breeding plan for Grevy's zebras, said he was surprised they died from the cold.
"Zebras are a pretty tough animal and can survive a range of temperatures," he said. "They can stand it in the 40s easily and maybe even the 30s." He noted that the National Zoo has an excellent record with Grevy's zebras and suggested that the dead zebras suffered from other problems that were exacerbated by the cold.
The last time the zoo lost animals in winter was March 1996, when spoonbills and scarlet ibises were released during a warm spell. "We felt the bad weather was over," Hoage said. "But then, we had a cold snap, and we lost four or five birds."
