Many young people know that conservation is necessary. Boy scouts in many countries study man and nature. These 'conservation volunteers' spend their spare time planting trees, building bridges, and so on. Some girls in a town in United States cleaned the banks of their river, and a group of boys in a village in Bangladesh mended a wooden bridge on a canal and cleaned the canal of debris. Actors, singers and writers in many countries have spoken about conservation. The popular English rock band, the Beatles and the singer Cliff Richard, have made records on conservation. The money from the sale of the records has helped conserve wild animals.