Secrets of Nature was a 1922–1933 British short black-and-white documentary film series, consisting of 144 films produced by British Instructional Films, which filmmaker, historian and critic Paul Rotha described in 1930 as "the sheet anchor of the British film industry". History The Secrets of Nature series was initiated in 1922 by Harry Bruce Woolfe, a former film distributor who had established himself with successful dramatised documentaries of the First World War, such as Zeebrugge and Mons, prior to setting up British Instructional Films in 1919 with the ambition of creating popular informational films. He recruited F. Percy Smith, who had established himself alongside fellow film pioneer F. Martin Duncan on the Urban Science series for Charles Urban before the war, to head up the series. Woolfe and Smith were joined by Natural History Museum curator W. P. Pycraft, ornithologist Edgar Chance, bird photographer Walter Higham, naturalist Charles Head, fellow Charles Urban Trading Company alumni H. M. Lomas of A Trip through British North Borneo (1907), and Woolfe's old friend, ornithologist and natural history cinematography pioneer Oliver G. Pike, who had established himself before the war with In Birdland (1907) and St Kilda, its People and its Birds (1908). He also obtained assistance from the entomologist Harold Maxwell-Lefroy. In 1929 former schoolteacher Agnes Mary Field, who had joined British Instructional Films in 1926 as its education manager and quickly learned all aspects of film production, took over from Percy Smith as editor of the series, in order to give him more time to concentrate on his photography, and lead the series into the sound era. Films The Cuckoo's Secret A 1922 British 17-minute short black-and-white silent documentary film, produced by British ornithologist Edgar Chance and shot by nature documentary pioneer Oliver G. Pike, featuring the nesting habits of the common cuckoo, which changed public perception of how the birds reproduce. Chance asked local children to watch nests around Pound Green Common so he could work out the ones the cuckoo was most likely to visit next and thus instruct Pike as to where to position his cameras to catch the best shots. The resulting footage provided the first documented proof that the birds lay their eggs directly in the nests of the species they parasitise, rather than laying them on the ground and carrying them to the nest, and inaugurated the new film series. The film was included on the 2010