Belarussian ornithologist Vladimir Ivanovski stands on a tree as he builds an artificial nest for birds of prey from an old bucket, in the snow-covered Elnya marsh, one of the biggest in Central Europe, near the village of Budy, some 230 km (143 miles) north of Minsk, March 29, 2011. Ivanovski has built hundreds artificial nests from natural materials such as tree branches, and from used old buckets too. REUTERS/Vasily Fedosenko (BELARUS - Tags: ANIMALS ENVIRONMENT SOCIETY)