ROSA burst into the living room, surprised me in my reading chair and, short of breath, blurted, “Do squirrels hide in grass?”She had been cutting our front lawn when a long, skinny, furred animal crossed the street and disappeared into a weed-covered lot.Now at the sidewalk, Rosa raised her arm to point out where the strange creature had gone, and at that very moment another one appeared, lopping over the asphalt and melting out of sight. A weasel!I soon learned that the official name of our newly discovered neighbor is long-tailed weasel in English; scientists know it as Mustela frenata. To Spanish speakers,it is a comadreja.Of the three species of weasels found in North America – the short-tailed, least and long-tailed – only the long-tailed ranges into Central and South America. Although all long-tailed weasels weigh less than a pound and have elongated slender bodies with chocolate fur, the ones in Costa Rica sport much blacker faces than their North American counterparts. Even so, they still display the white blazes on their cheeks, thought to resemble bridles by the scientist who named the species – hence the Latin epithet frenata.Few animal predators have the “killing machine” reputation of weasels. They can squeeze their bodies into the smallest of holes in pursuit of prey and kill things much larger than they are.I live just southeast of San Rafael de Heredia, north of San José, where urban sprawl meets coffee country. It’s probably no exaggeration to say that in this part of the Central Valley the weasel is the last wild remnant of the once diverse mammalian group Carnivora. Members of this order, also called true carnivores, set themselves apart by their special teeth: large, pointed canines and crested cheek teeth for tearing and slicing flesh.Before farms came on the scene, more than a dozen species of wild carnivores inhabited the Heredia area’s premontane forests. Otters swam in the creeks, jaguars stalked herds of peccaries, and black tayras climbed up trees. But because large-bodied carnivores need broad expanses of forest to survive, they began to disappear as farmlands expanded. At the same time, the animals that had been their prey were eliminated by hunting and deforestation.The weasel, however, was able to survive because it is small – difficult for people to shoot or trap – and adapts to non-forested habitats. Its adaptability hinges on a flexible diet, which consists of everything from insects, lizards and small snakes to birds, rabbits, rats and mice.BUT the weasels’ plasticity will not be enough when habitat changes become too drastic. The land beneath my house was apartially shaded coffee farm before it wassold to a developer nine years ago.The developer bulldozed the coffeetrees and put in roads, stormsewers and concrete streetpoles, anddividedthe landinto 98rectangularlots. As thelots waited tobe sold, grasses,asters, pokeweed, escobillaand small trees colonized them withtheir waist-high vegetation, providing protectivecover for rabbits and mice, as wellas sparrows, meadowlarks and quail. Inthis temporary state, much of this realestate offers more food and cover for weaselsthan do the monoculture coffee farms.However, as the inevitable constructionof houses begins to accelerate, theweasels’ ultimate demise seems assured.Of the 98 lots in my development, onlyeight had houses in the year 2001. By thetime I had built my house in August 2003,there were 18. Today the development hasnearly 50 finished houses, and I fear thetime to say goodbye to our stealthy neighborsis fast approaching.