ESCONDIDO - Lorikeets won't be landing on visitors to the San Diego Zoo's Wild Animal Park for the time being.

Ten of the park's small parrots have died in the last week, prompting park officials to close the Lorikeet Landing aviary until the cause of the deaths can be determined and the health of the approximately 40 remaining birds can be ensured.

Park veterinarians don't know what killed the lorikeets, but tests conducted by the county have ruled out West Nile virus, according to Don Janssen, veterinarian and associate director of the park's veterinary services.

The illness doesn't appear to be infectious, either, according to Janssen. If that proves true, it means whatever killed the birds cannot be passed on to humans, he said.

"We do see trends of death from time to time, and we go through a diagnostic process like the one we're going through now," Janssen said. "Often, we're able to come up with the cause."

The county tested the dead birds for West Nile, but the park has advanced diagnosis and pathology facilities of its own, Janssen said.

"Our resources are really rich here, and we've got them all on this one," he said.

Birds began dying eight days ago, a week after a Southern California heat wave. Janssen said the birds should have been able to withstand the heat. Their food may be another story.

"Perhaps the heat affected their food source, because it is a nectar … a perishable nectar," he said.

Lorikeets are native to Australia and the South Pacific islands. Adult birds stand about a foot tall. Lorikeet Landing is home to green-nape lorikeets, which have the green nape their name suggests but also have blue heads, red chests, and purple and yellow markings.

On Friday, after several more birds had died, parks officials made the decision to close the aviary.

"Pretty much the entire bird collection was moved to the hospital over the weekend," said Yadira Galindo, spokeswoman for the park.

The closure, which was followed by news reports about the lorikeet deaths, has prompted some calls from potential visitors worried about West Nile virus and wondering when the exhibit may reopen.

"We haven't had an overwhelming number of inquiries at this point, but people have been asking," Galindo said.

Janssen said it is too soon to tell when lorikeets will be restored to their aviary.

The park is home to nearly 300 species of birds, including about 20 endangered species. In 2002 and 2003, bird enthusiasts didn't get a particularly good look at most of them because the highly contagious Newcastle disease had infected North County poultry and officials at the park and zoo worried the disease would hit their bird collections, too.

Aviary exhibits that put birds and people in close quarters were temporarily shut down, in addition to other precautions such as removing chickens from the children's zoo.

Lorikeet Landing is a popular exhibit that allows visitors to hand-feed the gregarious birds, which grab nectar with a brushlike tongue not common among parrots.

Patty Monahan, who works at A Bird Haven, said that store's lorikeets are still healthy. She hadn't heard Lorikeet Landing was closed but could understand why the birds would be missed by park visitors.

"They're very playful, they have good temperaments and they're just funny birds," she said.

Contact staff writer Colleen Mensching at (760) 739-6675 or cmensching@nctimes.com.