The great blue heron rose easily off the reservoir as our horses approached. It flapped its wings gracefully a time or two before landing in a large oak tree. Soon tiring of its perch, it moved again, searching for the perfect vantage point in the warm spring afternoon. As its broad wings caught the breeze, it soared above us lazily.

Suddenly, a form dove from high above. A golden eagle snatched the heron from the sky and flew off, leaving behind only a puff of feathers and an astonished squawk from the ill-fated heron. Much as I mourned the beautiful heron, I marveled at the powerful eagle, simply and neatly fulfilling its natural instincts.

Since then, I've often thought about that incident and been grateful that my family's cattle ranch, sheltered in a narrow valley of the California Coast Range, is home to many species of wildlife. Among its varied wild residents are bears and mountain lions, Tule elk and mule deer, turtles and snakes, eagles and herons. When I was a child, it provided a nesting place for the few remaining California condors. Our hope is that it may always remain a refuge, a valley free from the development that threatens to smother so many beautiful places in California-and Colorado.

Over the last decade, Coloradans have fashioned many ways to protect open lands. We have voted tax increases to purchase open space, created, through a constitutional amendment, Great Outdoors Colorado (GOCO), to channel lottery funds to outdoor and recreational activities and donated conservation easements (which protect land from development forever) on thousands of acres of agricultural land. This is wonderfully exciting-and it is not enough.

Too often, we try to buy open space only after nearby development has driven land prices sky high. Small numbers of acres can cost millions of dollars to protect. While this land preservation is vitally important, it is also crucial to find ways to save large farms and ranches. Only with large blocks of land set aside forever from development will we be able to ensure the survival of wildlife and native plants that are vital to our environment.

Fortunately for Colorado, there are a number of efforts to maintain open space in harmony with growth and the needs of landowners. The Nature Conservancy manages land in the Yampa Valley and elsewhere, with an eye to protecting wildlife and agriculture. Colorado Open Lands has bought ranches near development and clustered housing in one area, leaving the rest as open space owned in common by the homeowners. The Colorado Cattlemen's Agricultural Land Trust holds conservation easements either donated by or purchased from ranchers. And the Gunnison Ranchland Conservation Legacy has bought conservation easements on thousands of acres of ranchland in development's path. Meanwhile, many more ranching families wait to participate.

That raises two key elements to successful preservation of agricultural land. First and foremost, the landowners must want to protect their land and must be able to set the terms for that protection. Second, because most ranchers are land rich and cash poor, there must be money available to purchase the conservation easements, allowing ranchers to continue in agriculture rather than selling out to a developer.

While some large landowners have generously donated conservation easements on their land, most cannot afford to do so. Herein lies the particular importance-and spectacular success-of Great Outdoors Colorado. It is by far the largest source of funds within Colorado for the purchase of open space and conservation easements. We Coloradans can be proud of what we created. But, time is short, given the intense growth pressures we face and the limited resources GOCO and our various land trusts have available. If we are to ensure the wide-open spaces that are refuges for wild creatures, we must move to protect agricultural lands before development pressure hits. We need to have a vision of Colorado twenty years hence and act on that vision now. If we focus our efforts on that vision, working with landowners, donors and funders, we can preserve what makes Colorado the best place to live in America.