The nest box was developed by a British conservationist, Charles Waterton, in the early 19th century to encourage more birds on his Yorkshire estate. Since then nest boxes have become widely used, particularly in Europe and North America, for two main purposes: (a) to enhance the conservation of cavity-nesting species by providing additional nesting sites to increase bird populations, and (b) to facilitate research on a wide range of topics from simple observations on breeding biology, growth of nestlings, moult, food and behaviour through to carefully designed research manipulations to answer complex life-history questions such as productivity, predation, parasitism, population limiting factors and competition.