The Mauritius scops owl (Otus sauzieri), also known as the Mauritius owl or Mauritius lizard owl, is an extinct species of scops owl that lived on the Mascarene island of Mauritius. Owls were mentioned in 17th-century accounts from Mauritius, a drawing was made around 1770 and a killed specimen was described in detail in 1837. After the owls had disappeared, subfossils were found in the Mare aux Songes swamp. These remains became the basis of the new species Strix sauzieri in 1893 and two other species were later named: Scops commersoni based on the drawing and description in 1896, and Strix newtoni based on a smaller fossil in 1907. Later writers doubted whether three owl species had lived on Mauritius, and these were concluded to represent a single species in 1994. It was placed in the new genus Mascarenotus along with the extinct owls of the two other Mascarene islands, the Rodrigues scops owl and the Réunion scops owl. A 2018 ancient DNA study found the Mascarene owls to be derived from different lineages within the scops owl genus Otus that originated in Southeast Asia, therefore not constituting their own genus, leaving the Mauritian species as O. sauzieri. Based on the contemporary accounts and subfossils, the Mauritius scops owl was a large owl with an average body length of 39.5 cm (15.6 in), larger than extant scops owls, and a wingspan of 59.4 cm (23.4 in). The wings were proportionally short and the legs were long. It had prominent, brown ear-tufts and featherless tarsi. The upper parts of its plumage were brown and the rest was wholly or partially white. Its white eyebrows (or supercilia) and bristles were unique among the owl species in the Indian Ocean region. Its skull and eye sockets were small for its size. Little is known about the behaviour of the Mauritius scops owl. Based on its long legs, it probably hunted lizards and small birds, like some other island owls. Their long legs and featherless tarsi indicate they were probably more terrestrial than other owls, and their proportionally small heads and eye sockets could indicate they were less nocturnal. The last two accounts based on observations state it had become scarce after formerly being plentiful, due to deforestation and poaching; it was gone by 1859. Researchers point to additional extinction causes, including the effects of introduced animals, and the increased terrestriality of these owls could also have made them more vulnerable.
Taxonomy A number of early reports mentioned owls on the Mascarene island of Mauritius, the first being those of the Dutch sailors Willem van Westzanen in 1602 and Cornelis Matelief de Jonge in 1606, and the British traveller Sir Thomas Herbert in 1627. No more owls were recorded until the French officer Paul de Jossigny illustrated various Mauritian specimens obtained by the French botanist Philibert Commerson around 1770, including the only known illustration of an owl from Mauritius. The French zoologist Julien Desjardins described a killed owl specimen in detail in 1837; his report and Jossigny's drawing were made widely known in 1896, after the owls had disappeared. The British ornithologist and Colonial Secretary for Mauritius Edward Newton mentioned in his diary that an owl skin was present at the Mauritius Institute until it was lost during a cyclone in 1870 (it is uncertain whether this was the correct year or if a storm was the cause at all), and no skins of this species exist today.
In 1889, the Mauritian government requested exploration of the Mare aux Songes swamp for "historical souvenirs", where vast amounts of dodo remains had been found. The new excavations, under the direction of the French naturalist Théodore Sauzier, were successful; apart from dodo bones, subfossil remains of other extinct animals, including previously known as well as new species, were found. These bones were sent to the Cambridge University Museum of Zoology, where they were examined and described by Newton and the German ornithologist Hans Gadow in 1893. Based on two humeri (upper arm bones), three tibiae (shinbones), and four tarsometatarsi (lower leg bones that fuse the ankle bones with the metatarsals of the feet), they determined the existence of an owl. Newton and Gadow stated that owls are generally classified according to features of the skull, sternum, or external characters, none of which were available for this owl. They noted the length of the tibia relative to that of the metatarsus is characteristic for various families and genera and indicated that the owl from Mauritius belonged to what they termed the "long-footed owls"; typical members of this group are the short-eared owl (Strix flammea) and its relatives. The Mauritius owl differed from those owls in some proportions, so Newton and Gadow named it as the new species Strix sauzieri. While the largest metatarsi were 63–66 mm (2–3 in) long, a pair were shorter and slenderer than the others at 56 mm (2 in), yet also fully ossified (turned into hard bone). These writers did not feel the differences were due to age or sexual dimorphism. Unless the island possessed two Strix species, the smaller bones would have to be from a small individual of the same species, although they found it unlikely that a species confined to a small island would range as much in size as the short-eared owl of Britain.
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