Othmar Reiser or Otmar Rajzer (21 December 1861 – 31 March 1936, Pickern) was an Austro-Slovenian ornithologist and naturalist who worked as curator of the bird collections in the natural history museum at Sarajevo, working there from its foundation for thirty-three years during which he explored various regions including the Balkans and South America and collected specimens.
He studied at the local gymnasium, at Novo Mesto (matriculating in 1882) and then joined as a reserve lieutenant in the 47th Infantry Regiment.
He was involved in founding the National Museum of Bosnia and Herzegovina in Sarajevo and then joined its department of Natural History and worked there until retirement in 1919.
He also collected plants and was in charge of the herbarium after the death of the botanist Franz Fiala.
[2][3] In 1903 he took part in an expedition of the Austrian Academy of Sciences to north-east Brazil, during which he was the first to observe the Spix's macaw in the wild since its original discovery 84 years earlier.