 The existence of more than 40 species of birds and other wildlife is in peril. Their survival depends on whether or not the wine cork survives. And yes, by that I mean the stoppers used in wine bottles. Corks have been used since the early 1600s. The Benedictine monk Dom Perignon first used it to seal his bottles of sparkling wine. To date, plastic threatens to replace natural cork. Natural wine corks are made from the bark of a type of oak tree found in the western Mediterranean, mostly in Portugal, Spain, and Algeria. All of the cork harvested in the Mediterranean is sold to Portugal, where a handful of producers make half of the world's annual supply of wine corks, 13 billion to be exact. To make a cork, the manufacturers strip the bark from the trees, season it for six months or so, then boil it to kill mold and insects. The corks dry for three weeks in a warehouse, then are sliced into strips from which corks are punched out and polished. But then the trouble starts. Traditionally, they bleach corks in chlorine to kill bacteria and to improve the cork's appearance. What can happen, though, is a special mold can grow from the leftover chlorine. It is this mold that has given plastic an inroad. The mold, called tri-chloral anisol or TCA for short, can ruin a bottle of wine. It makes it taste like a cellar or damp cardboard. It doesn't take much. A single tablespoon would destroy all the annual wine production of the U.S. Plastic corks, of course, don't form this mold. This battle of natural cork versus plastic has serious consequences. 85% of the world's wine corks come from Portugal. This accounts for 3% of their GDP. A huge number of natural corks are still used. Only one bottle in 20 has a plastic stopper, but the trend is toward plastic. The battle isn't only for the well-being of Portugal's economy. The increasing use of plastic stoppers puts wildlife at risk. For centuries, the cork woodlands in Spain and Portugal have provided shelter for many species of birds. The cork forest provides sturdy, tranquil nesting sites, while the grasslands are ideal hunting grounds. Some birds have adapted to nesting almost solely in cork trees. Cork farmers carefully nurture and sustain their trees because it takes 25 years for the bark to be good enough to harvest. After that, they can harvest only every 9 years. But if natural wine corks are no longer economically viable, the cork trees are not likely to be replanted as they naturally die out, leaving large sections of natural forestland prey to other economic uses that don't need trees. So to save an endangered bird, go to your local wine shop and buy a bottle with a real cork.