Four peregrine falcons now cruise the sky over Baltimore, occasionally sweeping down from hundreds of feet at a speed of 175 miles-per-hour to catch a rat or a pigeon.

It is a clean kill. The incredible impact of the talons breaks the victim's back. The meal is usually eaten at the falcon family's nest on the 32nd floor of the U.S. Fidelity and Guaranty Insurance Building above Inner Harbor.

Baltimore's peregrines, rare birds, attest to the growing interest in bringing wildlife back into cities and ksuburbs. The Fish and Wildlife Service, traditionally concerned mostly with the fishing and hunting industries, now has an urban, "non-game" wildlife specialist on its staff. There is an Urban Wildlife Research Center in surburban Washington. And several states, notably Missouri, make well-funded efforts to the make the human habitat more hospitable to free-born animals.

Scarlett, a falcon originally released two years ago on the Maryland shore by Cornell University's Falcon Fund, was the first to settle on top of Baltimore's USFG building. She wanted to live where the action is, but did not seem to like the single scene.

Cornell, obligingly supplied a male, a young falcon named "Red." "Scarlet liked him all right, but their eggs were infertile," said Thom Cade, who heads the Cornell program to bring the all-but-extinct peregrine falcon back to America's Eastern seaboard. "So we brought her some fledglings from our laboratory for adoption. They seem a happy family."

Last year's attempt to settle four young peregrine falcons on the top of Washington's Interior Department building did not, however, have a happy ending. Two of the birds were found shot hundreds of miles away. The others disappeared. So did four young peregrines placed on the Smithsonian castle tower on the Mall after the Cornell students who placed them there went back to school.

Quite possibly the young falcons were scared away from Washington by too much press attention. One commentator complained that the government had no business subsidizing wild animals which might upset pigeon-loving citizens.

Natural ecological control of rats and pigeons would surely be less hazardous -- and perhaps more humane -- than chemical poisons. Germany, I am told, has started a program to settle more birds in swamp areas, rather than spray DDT to keep mosquitos in check. But it would take an awful lot of urban falcons according to Cade, to rid American cities of what the experts call "nuisance animals."

The best way to control starlings, pigeons and sparrows is to build fewer widely spaced vent holes, exposed beams, ledges and other invitations to roost. The best way to fatten fewer rodents is to reduce tasty litter and improve garbage disposal.

"The reason we are trying to bring peregrine falcons into the cities -- there are also a few in New York -- is because we found that they are safer there," said Cade. Predators cannot get up on skyscrapers as easily as on they can get up on natural cliffs. There is not as much poison in the food chain as there is in rural areas. And there are plenty of pigeons and small mammals for them to eat."

Other birds, too, often prefer an urban setting to a rural one. Wood thrushes, larks, gold finches, cardinals and many other species find more varied food and more opportunities to nest in landscaped suburbia and in city gardens than out on rural land, said Daniel L. Leedy, of the Urban Wildlife Institute. Out in the country you -- and the birds -- are likely to find large areas with nothing but fields of the same crop or dark woods without underbrush. Residential developments, in contrast, have all sorts of shrubs and bushes, berries and seeds to sustain all sorts of birds.

"Bird feeders help a lot, too," said Lowell W. Adams, another wildlife biologist. "We estimate that one out of five American household help support birds. That makes a lot of difference."

Dr. Aelred D. Geis of the Fish and Wildlife Service said people often spend more money than necessary on commercially packaged bird food. "For instance, birds prefer inexpensive, oil-type sunflower seeds to the more expensive white striped sunflower seed that one usually gets," Geis said. m"They also like thistle feeders with vertical perches better than the usual, elaborate feeding stations."

The best thing people can do to attract birds is to let their grass grow. Manicured lawns are just not for the birds. "I wish meadows, rather than lawns, would become fashionable," said Geis. Grass and weeks produce an abundance of interesting things for interesting birds to eat.

This is also one of the messages urban wildlife specialists have for highway departments. They could save millions of dollars a year on moving and thereby create a better environment for birds and other small wildlife on the millions of acres of land that lines America's roads. Hedge rows, rather than concrete barriers, provide habitats for animals without cutting off their accustomed rounds.

The experts are also working on ways of saving both motorists and animals from often deadly collison. "Out West, wildlife planners have found that deer and other animals can be coaxed to use underpasses rather than get themselves killed trying to cross interstates," said Geis.

Animals, it seems, are quick to adapt to the urban environment. They do not seem to mind noise, for instance, any more than most humans. They are oddly indifferent to automobiles. It is no longer rare to see deer inside the Washington beltway. Raccoons and their antics are as steady a cocktail party topic in Georgetown as coyotes and their howling are in Beverly Hills. pMore and more city city planning commissions are following the new research guidelines on urban wildlife planning.

Simple and often relatively inexpensive measures -- such as providing "edges" of underbrush along building concentrations or parking lots or planting one kind of shrubs rather than another -- can go a long way towards a harmony between humanity and nature.

As the world is becoming increasingly urbanized, some degree of this harmony is a matter of survival for humans as well as animals, I believe. It is not just a matter of deriving enjoyment from watching song birds at their feeders, squirrels chasing one another in their trees, or ducks proudly parading their young in park ponds. This enjoyment, as urban wildlife advocates point out, has measurable financial benefits; it increases real estate values.

But far more than that is at stake. Living with creatures that are free and do not readily submit to human will and dominance is a very special experience, particularly for children. A Canadian psychologist offers evidence, as if evidence were needed, that children who have this experience of delight and discovery are mentally and physically healthier than children whose acquaintance with the animals is limited to dogs, cats, sparrows and rodents.

Concern and consideration for animals other than pets in our midst is the beginning of concern and consideration of maintaining the balance of nature. Like the trees and the sky, it gives us a sense of being a part of nature, a part of the unfathomable wonder of it all, rather than being another miraculous but malfunctioning product of technology, like a farecard.