The director of the National Zoo announced yesterday that she will appoint a new curator to oversee all operations involving animal care, a major overhaul prompted by the recent accidental poisoning of two red pandas that raised concerns over how well animals are being protected.

But even as the director, Lucy H. Spelman, outlined organizational changes to better protect the animals, zookeepers were dealing with yet another death, the eighth in recent months. This time it was a pygmy hippopotamus, a 9-year-old female that was found dead yesterday morning in the Elephant House.

A preliminary necropsy conducted yesterday on the 600-pound pygmy hippo showed that it suffered from pulmonary congestion and edema, meaning fluid had built up in its lungs. The exact cause of death will not be known until the zoo's pathologist completes additional tests and tissue studies, officials said. Pygmy hippos can live 40 years or more in captivity.

While deaths in a zoo are not uncommon, the concentration of fatalities over such a short period has brought unwanted scrutiny to an institution renowned for animal care and research. Human error is to blame in the deaths of the red pandas, but concerns have been raised about some other fatalities.

"Several of these deaths were sad, but not all of them were surprise deaths," Spelman said, "Animals live and die, but when we lose an animal, it's my job to make sure we're paying the best attention to details."

The new "general curator" will supervise the zoo's eight other animal curators. Pest control operations will be moved from the safety office and placed under the direction of the zoo's pathologist.

The general curator, Spelman said, will "strengthen the focus on day-to-day animal care by giving us someone to manage all of our curators."

The recent problems, she added, "have shown us we need to get back to basics and need to see what is happening on a daily basis. We're reviewing every written procedure and every practice."

One huge failing, she said, was that the contractor who buried the poison violated zoo policy by going into the yard without a keeper or other animal staffer being present -- a staffer who would not have permitted such an action, she said.

"That will never happen again," Spelman said. "It's very basic zoo operation. You don't go into an exhibit area without animal staff there."

Spelman also said that she had discovered the pesticide contractor was not certified to use the poison and that from now on, she will personally review the licenses of all contractors and sign off on the use of any chemicals anywhere in the park.

The adult male red pandas were found dead in their yard Jan. 11, less than 24 hours after pellets of aluminum phosphide -- which mixes with groundwater to form a toxic gas -- were buried in the yard to control a chronic rat problem. Three zoo employees who went inside the yard the next morning experienced headaches, nausea and diarrhea and were treated at hospitals and released.

The zoo has been working with its parent organization, the Smithsonian Institution, to investigate the deaths. But Spelman, formerly the zoo's chief veterinarian, said she "wasn't going to wait" to make changes.

"It was extremely poor judgment to even consider using the pellets near animals," Spelman said. "Experienced staff in supervisory positions chose to put it in the enclosure with animals, and because of that we're changing how we supervise our curators and supervise the health and safety and care of the animals."

A spokesman for the D.C. Public Health Department, whose inspectors have worked with the zoo to make sure the red panda enclosure is no longer contaminated, said the contractor was not licensed to do business in the city.

Spelman said the pellets were placed in the red panda yard without her or most of her senior staff knowing. It was the first time a poison was used inside an animal enclosure, and Spelman said the decision was made without consulting veterinarians.

Spelman said certain personnel actions were being taken as a result of the red panda poisoning. She declined to elaborate but said that some experienced zoo personnel and supervisors knew about the poison and that changes are being made. "In not too much more time, it will be clear to everybody what steps I've taken," Spelman said.

In addition to the red pandas and the pygmy hippo, a lion died in October because of complications after anesthesia. Two adult giraffes died within seven months last year because of age-related digestive problems, and zoo officials are studying whether changes in their diet or dental care might have prolonged their lives. A white tiger was euthanized because of age-related osteoarthritis, and a gray seal died of heart disease.

Also, in the winter of 2000, two young zebras died at National Zoo facilities after keepers failed to feed them enough fat and protein to keep them warm on frigid nights.

Spelman said zoo pathologist Richard J. Montali and the new curator, as yet to be hired, will be part of her senior staff. She also said food preparation for the animals will be supervised by the veterinary staff, with the animal nutritionist reporting to the chief veterinarian.

David L. Evans, the Smithsonian's undersecretary for science, said Spelman "is doing a terrific job under trying circumstances. . . . Everyone at the zoo from Lucy on down is there because they care about animals."

The pygmy hippo found dead yesterday was the last of the species born at the National Zoo and was the only one kept at the Elephant House. The zoo has two Nile hippos on exhibit at the Elephant House. DEATHS AT THE ZOO The National Zoo director ordered an overhaul of animal care in response to the deaths of two red pandas this month. In recent months, eight animals have died, including a pygmy hippopotamus found dead yesterday morning. Pygmy Hippopotomas Jan. 27: Preliminary tests show the pygmy hippo died of pulmonary congestion and edema. Red Pandas Jan. 11: Two red pandas found dead after rat poison pellets that emit toxic fumes were buried in their yard for the first time. Lion Oct. 11: A 14-year-old lion died a day after a complete medical checkup. A preliminary necropsy found that Tana's death was due to an unexplained buildup of blood and fluid in his lungs. White Tiger Oct. 2: Taj, an 18-year-old white tiger, was euthanized. He was treated for osteoarthritis for several years and was having trouble walking. Gray Seal Sept. 3: Keltie, a 23-year-old gray seal considered to be in late middle age, was lethargic, ate little and swam with difficulty. DIgestive problems were cited as cause of death. Masai Giraffe Sept. 2: Griff, a 19-year-old Masai giraffe, had eaten poorly from her feed of pellets, alfalfa hay and leafy branches for a week before she collapsed and died. SOURCE: Staff reports

The latest death at the National Zoo -- a 9-year-old female pygmy hippo -- was discovered in the Elephant House.