They ride through the wilds of Wheaton and Silver Spring, spurring on horses named Apache and Trigger, jumping over downed tree trunks and splashing through streams. In the populous heart of eastern Montgomery County, there are still rough riders dedicated to keeping the suburbs safe from more sidewalks.

Modern times have been tough on America's backyard horses. Commercial development and zoning restrictions have significantly reduced their rural range. Spiraling costs and a European market for American horseflesh have made them increasingly expensive to buy and keep.

But horse owners in Montgomery County, particularly the eastern, more suburban half, have been holding fast to their hard-won trails with persistence worthy of the U.S. Cavalry.

"All of us are in jeopardy," said Pat Oliva, a 45-year-old emergency room nurse who helped found an association of suburban horse owners called Trail Riders of Today two years ago. "That's why we formed TROT. One day, you'd be riding through an open field. The next day there'd be developers' markers there. And the day after that the bulldozers would come."

In two years, TROT members have spent almost as much time on political lobbying as riding trails. The organization has 16 committees responsible for such activities as fund raising, public relations and keeping track of state legislation. Members regularly appear before the county's planning commission to ask that equestrian trails be included in all new housing developments.

"They have done a very good job lobbying," said Tom Robertson, an official with Maryland-National Capital Park and Planning Commission. "What they're faced with is the potential loss of their network of trails."

There is no accurate estimate of how many horses or trail riders there are in Montgomery County. TROT has a membership of nearly 300, but some of them live in Prince George's, Frederick and Howard counties. And TROT only represents a minority of horse owners. Getting accurate figures is difficult because many horse owners are reluctant to be counted. In Montgomery County, for instance, zoning regulations require homeowners to have a minimum of two acres before they can board a horse. More than a few horse owners fall short of that requirement.

But trail riders are used to skirting private land and public law. Until recently, when their political efforts began to pay off, they rode on the fringe of the law.

"We knew we were illegal and we knew we weren't allowed to ride where we were riding," said Oliva at a recent meeting of TROT members at her Silver Spring home. "But now we have got to present ourselves as a group of law-abiding citizens."

While TROT has been successful in legally opening an estimated 100 miles of trails in Montgomery County to horses, other pressures on owners have continued to build. Perhaps the most damaging of those has been the European market for horse meat that has made even mediocre-quality backyard horses valuable commodities.

"Today, it's hard to find a nice pony for $500," said Lowell Gobble, a Virginia state extension agent. "Horse butchers are paying anywhere from $300 to $500 for an animal that could be bought as a good pleasure horse for $150 10 years ago."

A report issued by Virginia Tech last fall concluded that it costs about $3,000 a year to keep a horse, and that the number of horses, mules and donkeys kept in Virginia has declined by more than 28 percent in 10 years.

"The moneyed people are still going full steam, buying million-dollar yearlings and charging $50,000 stud fees," Gobble said. "But the less affluent are finding it takes more dollars to live, leaving less for luxuries like horses."

Most of TROT's members are decidedly in the less affluent set. Few enter horse shows or ride to the hounds. Most are more like Frank Schell, a 64-year-old carpenter who says he rode a horse from his home in Olney to Sherwood elementary school in the second grade.

"I've never been without a horse since I was five years old," he said.

Another TROT member, 30-year-old Cathy Diamond, won her first horse in a name-the-pony contest at a Detroit Pistons basketball game. Diamond was in the first grade, living in suburban Detroit, when she came home with "Hook Shot." She now lives in Silver Spring two miles from where she boards her current horse, a 5-year-old, dappled-gray Arabian called Trade Winds.

Four or five afternoons a week, Diamond leaves her 16-month-old twins with a neighborhood baby sitter and saddles Trade Winds for a ride through fields and woods that many residents of Montgomery County would be surprised to know still exist.

"The kids mow you down after a while; you need a break," Diamond said last week, after galloping down a trail lined with white oak and evergreen. "When you come out here and see deer and pheasant, it's easy to forget about everything else."