A partridge in a pear tree is Christmas tradition, but an ostrich in the evergreens is a bird of a different feather, the authors of America's most famous Christmas catalog discovered yesterday when their gift-of-the-year laid an egg.

In the never-ending search for something new and weird to put under the tree, the wonderful people who brought you his and her hot air balloons, matching windmills and the 11-foot-pole came up with this year's Texas trinket: ostriches.

Only $1,500 a pair from the 1980 Neiman-Marcus catalog.

Ostriches "love ranch life," the new catalog promises. With a pair of your very own, you can "stage impromptu ostrich races, learn the original Watusi dance derived from their flamboyant courting ritual, revive quill pens for writing."

The ostriches are being raised by the Monastery of the Holy Protection of the Blessed Virgin Mary, in consultation with the Oklahoma City zoo, the catalog adds.

The big birds lay 20 or 30 egss a year, so "it won't take long to count heads of ostriches," Neiman-Marcus says. If you'd rather not be overrun with ostrichettes, each egg is as big as two dozen Grade A Large chicken eggs, so "you can have one-egg omelet parties." When you get tired of buying birdseed for the 300-pound canary's cousin, just give the bird to "your favorite zoo," the catalog suggests.

The ostrich order blanks went in the mail last week and promptly landed in the nest of a flock of bird lovers, who've been screeching ever since.

Not since an Interior Department endangered species herpetologist found a rattlesnake on the menu at Dominique's has such a cursed critter suddenly become so beloved.

The Fund for Animals, The Defenders of Wildlife and the Humane Society of the United States all have their feathers ruffled.

"I suggest one of the Marcuses put their head in the sand immediately, squawked Cleveland Armory, founder and president of Fund for Animals.

"Almost all of Neiman-Marcus's ideas about animals are outrageous," he said, accusing the chain of catering to the kind of people who demand boots and belts from the pelts of exotic animals. "If they could make a fur coat out of people, they probably would," grumbled dogs' best friend.

The Humane Soceity complained that the baby ostriches offered by Neiman-Marcus are likely to meet the fate of Easter bunnies or baby chicks, most of which die of malnutrition or abuse. Worse yet, the chick could grow up to be a full-grown ostrich, which Society President John Hoyt said "is not a living version of Sesame Street's Big Bird."

"These birds can unzip your entire body with one swell foop," cringed Sue Pressman of The Humane Society. "These monsters can weigh 300 pounds. They're inappropriate as a gift."

"Ostriches can kill you. They'd make terrible housepets," warned Heidi Hughes of Defenders of Wildlife, which is opposed to anyone keeping wild animals as pets."

Most zoos don't want cast-off pets, she said, and harboring an ostrich is illegal in many places, including Fairfax County, which bans all "exotic pets."

Meanwhile, back at the ranch, Neiman-Marcus marshalled a public relations posse to head off the stampede.

Keith Nix, Neiman-Marcus vice president for public relations, said he didn't reallly understand what all the fuss is about. He insisted the store would never sell a bird to anyone who didn't have a game preserve or zoo lined up to keept it in.

"We would never sell it to someone who planned to keep it in a back yard," Nix said.

He noted that this isn't the first time Neiman-Marcus had offered living creatures for that someone who has everything.