When Alice Bird is asked how she diverges from her opposition in the upcoming Board of Supervisors election in Loudoun County, she recites a number of differences, each beginning: "My opponent . . . . "

What she does not say -- until she is asked -- is that her opponent is her former husband.

Andrew R. Bird III, a two-term Republican who represents the Sterling District, and Alice Bird, who is challenging him as an independent, hold the distinction of being the only divorced couple running against each other on the Nov. 3 ballot in Northern Virginia, if not the entire state.

The Birds were divorced last year after 15 years of marriage.

"It's an unusual situation," acknowledged Andrew Bird. "It's not becoming an issue, but it's becoming a curiosity."

Alice Bird, a registered nurse at the Reston Hospital Center emergency room, says that she is not running against her former husband "out of spite" and that she decided to enter the race only after she heard that he planned to run for the state Senate.

When he decided to seek a third term as supervisor instead, "I was sort of surprised," she said. "But it didn't change my mind. I'm running because I'm more sensitive to the needs of the Sterling District."

Andrew Bird, currently vice chairman of the eight-member Loudoun board, represents the county's smallest magisterial district -- two square miles of dense development that lies hard by the Fairfax County line, just south of Rte. 7.

The district has nearly 3,650 registered voters and a population of about 9,000. Four years ago, there were 3,044 registered voters in the district.

The curiosity of their marital history aside, the Birds sound much like any other opposing candidates in Northern Virginia's local races this year. In Sterling, as elsewhere in the area, growth is the primary issue.

Andrew Bird, 42, is running on his record of shaping the development that is quickly spreading westward across Loudoun, toward Leesburg. Alice Bird, also 42, claims that the county's growth is unchecked and that the incumbent has been too soft on developers, too quick to welcome them into the county.

"We need to slow growth and development, but not stop it," she said. "Growth and development are a sign of progress. But developers come in here and fatten their wallets."

Andrew Bird said that it is "axiomatic {that} everything east of Leesburg and north of Dulles Airport is going to develop. The question is how."

The planning process should "be designed to get things done, not to obstruct," he said, adding that he favors development in eastern Loudoun around "three nodes," his term for the multiuse Xerox complex north of Rte. 7, Dulles International Airport and the intersection of Rtes. 7 and 28.

"If you focus development around these nodes, you have gone a long way toward solving transportation problems. Your traffic flow is freer," he said.

"One of the keys to Loudoun's future is that development has to be balanced," he added. "We must offset the residential development with commercial and business development."

Currently, the commercial-industrial real estate tax base in the county is about 25 percent, according to William C. Gardner, county assessor.

The opportunity to shape Loudoun's growth is the major reason he decided to run for a third term, Andrew Bird said. "What happens during the next four years will determine what happens for the next 50 in Loudoun County. I'd like to stick around to finish the job I set out to do . . . . County government is where the action is, where you can accomplish something," he said.

Bird said he decided not to run for the state legislature because, "as a freshman in the minority party, I wouldn't accomplish much."

Andrew Bird's accessibility to constituents has become an issue in his race against his former wife, according to Eleanor Bryan, a member of the county Democratic committee, which has endorsed Alice Bird.

Bryan said she voted for Andrew Bird four years ago, when he defeated Carolyn Lehner with 65 percent of the vote. But Bryan said she plans to vote against him this time, adding: "Many people have tried to reach Andrew Bird on constituent matters and have been unable to or, if they have, they have not been satisfied."

Alice Bird echoed Bryan on that score. "My opponent is not responsive -- on sidewalks, on potholes, on speeding traffic on the Lincoln Avenue 'bypass,' " she said. "We need a supervisor to spend more time in the Sterling area."

Andrew Bird, an estate planner with a Tysons Corner insurance firm, says he is no less accessible to constituents than are the other board members. He acknowledged that during his divorce proceedings he lived with his parents for a time, elsewhere in the county. He is now remarried and living in Sterling again.

He said that "an interruption in domestic tranquility {made} lots of things difficult" during the past few years.

Alice Bird gives her opponent credit on some fronts: "He led the fight against a HUD Section 8 development in 1981, and I supported him. But he said if low-rent HUD housing came in for the elderly, he'd support it, but he has not."

A Methodist housing agency plans to use U.S. Department of Housing and Urban Development subsidies for a 91-unit project for the elderly. Andrew Bird says he has some reservations about the project, which is planned for his district.

"You may think HUD is going to take care of your own people, but they don't always," he said. "They don't honor county lines.

"I had some concerns with HUD in 1981" over the proposed Section 8 housing, which was not built. "There is no reason not to view HUD with a jaundiced eye now."

Neither campaign is bringing in major contributions, according to the candidates. Alice Bird, who is serving as her own campaign manager, said she has raised slightly more than $2,300; Andrew Bird said he has commitments for $2,500, with $1,200 in the bank.