You can tell a lot about a Coloradan these days by the rear of his car.

First, there was the bumper sticker that read "Native." That was the creation of the three-year-old Colorado Native Society, a small but hardy group dedicated, its platform says, to "preserving and improving the quality of life in Colorado."

Sensing many dollars in need of spending, a young entrepreneur followed the society's lead with "Semi-Native" stickers, designed to indicate that a person had been around a while but wasn't, strictly speaking, a native. Inevitably, "Alien" stickers soon followed, for the unashamed newcomer.

The battle of the bumpers is a polite version of a larger struggle in Colorado between the vast numbers of newcomers who have brought white-collar skills and ambition to this money-conscious region and people who pre-dated the boom --not all of them natives -- who fear that their identities are being swallowed up amid the New York lawyers, Texas oil men and Canadian land speculators.

"It rubs me the wrong way," said W Mitchell, who does not use a first name and says the W doesn't stand for anything. He's the Pennsylvania-born mayor of the tiny mountain town of Crested Butte. With some natives, he said, "it's as though because they popped out on the delivery table in Colorado they are somehow more deserving than someone born two miles across the border in Utah or 2,000 miles away in Pennsylvania."

At department stores, gas stations and record shops throughout the Denver area and some other parts of the state, "Native," "Alien," "Semi-Native," "Naive," "Restless Native" and other stickers cost $1.50 each. The most recent and one of the most popular says simply, "Who Cares?" All the stickers are modeled on the Colorado license plate, with white lettering on a green mountain silhouette against a white sky.

Concerned that "we were becoming an endangered species, tired of people saying, 'Gee, you're the only native I ever met,' " Eleanor Hazlewood, 25, a phone company employe, joined the 500-member Native Society in 1979 and now is its president.

The society, which requires a Colorado birth certificate for membership, put out the original "Native" bumper sticker in 1978 as part of its $18 membership package. Budding capitalists came from all over to copy or expand on the idea, and the society is miffed by the "Alien" and "Who Cares?" stickers.

"They are political and mean," Hazlewood said.

But David Greenberg, 31, a native New Yorker who has been in Colorado most of the past 10 years, including a stint as counsel to the governor, argues that longtime residents have profited handsomely from the money and business brought in by outsiders during the boom of the last 15 or so years.

Colorado's population increased by 30.7 percent between 1970 and 1980, according to census figures. By far the fastest-growing age group is people 20 to 34 -- in large part well-educated young professionals whose influx into white-collar and energy-industry jobs has created a bonanza of related jobs for many natives.

Money and growth notwithstanding, a tension has emerged between those who are newly arrived and those who were here before the boom.

"Colorado is the fad place to come, like California used to be. It's very transient, so people don't care as much" about things like clear air and recreation areas, Hazlewood said.

Again, Greenberg disagrees:

"If anything, the newcomers are more fanatical than the natives about preserving Colorado's good things. My generation came here for the lifestyle, so we're bound to work hard to maintain it."

A letter to the editor of a Denver newspaper following a story about the Native Society is indicative of the ill will between the groups. "One of the best indications that a community is populated by a bunch of hicks is its preoccupation with the virtues of being a native son," a newcomer wrote.

The real lesson from this "more Coloradan than thou" competition: in a state having money to burn, a buck fifty is a small price for a declaration of pride.