GRAFENAU, Germany -- It has been 20 years since the Berlin Wall fell. But deep in the forest here, a red deer called Ahornia still refuses to cross the old Iron Curtain.

Ahornia inhabits the thickly wooded mountains along what once was the fortified border between West Germany and Czechoslovakia. At the height of the Cold War, a high electric fence, barbed wire and machine-gun-carrying guards cut off Eastern Europe from the Western world. The barriers severed the herds of deer on the two sides as well.

The fence is long gone, and the no-man's land where it stood now is part of Europe's biggest nature preserve. The once-deadly border area is alive with songbirds nesting in crumbling watchtowers, foxes hiding in weedy fortifications and animals not seen here for years, such as elk and lynx.

But one species is boycotting the reunified animal kingdom: red deer. Herds of them roam both sides of the old NATO-Warsaw Pact border here but mysteriously turn around when they approach it. This although the deer alive today have no memory of the ominous fence.

Ahornia, a doe with a grayish-brown winter coat and a light patch around her tail, was born 18 years after the fence came down. Wildlife biologists who track her and other deer via electronic collars know that she has never ventured beyond the strip where the fence once stood.