Towards the end of the 19th century, Andersen first worked as an ornithologist and ran field studies on the Faroe Islands. In 1901 Ferdinand I awarded him an appointment at the Zoological Museum of Sofia. Due to his frustration with the working conditions, he gave up this position.[1] In 1904, he was hired by the British Museum to research bats in the Pacific, in South-East Asia and in Queensland. He was especially interested in the genus Flying Fox and Horseshoe bats, of which he described 15 new species. He published 13 scientific papers on the South-East Asian Horseshoe bats. His most famous work was his Catalogue of the Chiroptera in the Collection of the British Museum, which is considered one of the most extensive works on flying foxes. Andersen was elected fellow of the Zoological Society of London (ZSL) in 1909.
In June 1918 he mysteriously disappeared; his body has never been found.[2] His colleague Oldfield Thomas submitted his final manuscript on his behalf and stated that Andersen expected "to be absent from his scientific work for some time."
^Jon Fjeldså: Danske ornitologer langt fra hjemmet: fra P.W. Lund til international fuglebeskyttelse In: 100-års festskrift Dansk Orn. Foren. Tidsskr. 100 (2006):S. 265-275
^Flannery, T. (2012). Among the islands: adventures in the Pacific. Grove/Atlantic, Inc. ISBN9780802194046.
