- Principe Scops-Owl
 - Principe Scops-Owl

Principe Scops-Owl Otus bikegila Scientific name definitions

Bárbara Freitas and Martim Melo
Version: 1.0 — Published October 24, 2023
Revision Notes

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This insular scops-owl was a newly described addition to the Otus genus in 2022 (1). It is endemic to Príncipe, the northernmost of the three oceanic islands of the Gulf of Guinea in central Africa. Each of the other islands has its own Scops-Owl species: Sao Tome Scops-Owl (Otus hartlaubi) on São Tomé, and a subspecies of the African Scops-Owl (Otus senegalensis) on Annobón. Curiously, phylogenetic analyses have shown that Príncipe was the first of the Gulf of Guinea islands to be colonised by a scops-owl (1). A typical scops-owl, close in appearance to the Sao Tome Scops-Owl, the Principe Scops-Owl occurs in two color morphs - a deep rufous morph, and another where the upperparts are rufous and the face and underparts are mostly gray. Its ear tufts are rarely seen in the wild, except in exceptional circumstances. The diagnostic feature is its repetitive and fast-paced single note call, emitted as soon as darkness falls and throughout most of the night.

Principe Scops-Owl is restricted to the highest quality native lowland forests located in the uninhabited southern half of the island - a distribution that explains why it took so long to find the species, but also reflects its susceptibility to human disturbance. Its actual area of occupancy may be no more than 15 km2 (2), making it one of the species with the smallest range in the world. Still, in this small area, it is relatively common and its calls a defining feature of the night soundscape. It is highly territorial, as with most species in the genus, and the little available data from ringed birds suggests already that individuals have a high site fidelity.

The presence of a candidate species of owl on Príncipe Island was only confirmed in 2016 (3, 4), following decades of the accumulation of evidence pointing towards it. In 1998, while studying the Gray Parrot (Psittacus erithacus) from Príncipe, Martim Melo collected testimonials from Ceciliano do Bom Jesus (known as Bikegila) describing two occasions, in the early 1990s, when parrot harvesters had found a bird unknown to them in the tree holes where they were looking for parrot chicks. Both these events took place in the southern forests of the island (Ribeira Porco and Focinho de Cão), the main parrot breeding site (5). In one instance, Bikegila himself was present and the description of the bird fitted the overall appearance of a small owl. Sátiro da Costa was responsible for the second observation, and when presented with the color plates of the endemic birds of the Gulf of Guinea islands (6) immediately identified it as the Sao Tome Scops-Owl (Otus hartlaubi). He also reported that some elders told him it was a “Kitóli” (the name given on São Tomé Island to Sao Tome Scops-Owl), and that it destroys parrot eggs to occupy the nesting cavity, suggesting that there was some local knowledge on the species (5). In 2002, Martim Melo heard and recorded unknown calls in the area of Ribeira Porco. Notes of these calls were in the same frequency range as those of other scops-owls (Otus), but were distinct from those of any known species (7, 8). In 2007–2008, a survey of the island was carried out to determine the distribution and abundance of the Principe Thrush (Turdus xanthorhynchus) (9), and to determine the source of the putative owl-like calls (7, 8). These calls were mapped and new recordings obtained, but the individuals emitting these calls remained unobserved.

In 2009, in an effort to unveil independent evidence for the presence of an owl on Príncipe, Rita Covas (CIBIO-InBIO, Portugal), at the request of Martim Melo, unearthed a letter by José Correia in the archives of the American Museum of Natural History (AMNH), New York. In 1928–1929, Correia and his wife Virginia collected in the Gulf of Guinea for the AMNH. Their collection was the basis for the first synthesis on the origin of the birds of the islands (10). In a letter from Príncipe Island, dated 3 Oct 1928, he reports to Gordon Cushman Murphy that although he did not see any owl on Príncipe, some residents told him about its presence in the “wild forests”, where it could take them up to ten years before they could find one (11). This information had no impact whatsoever, and the letter was archived with no efforts to pursue this lead. Similarly, the ornithologist René de Naurois, who did extensive work on the islands in the 1970s, never saw an owl on Príncipe, but did collect four third-party potential sightings, all from the northern part of the island (12, 13). With hindsight, the Principe Scops-Owl (Otus bikegila) is restricted to the old-growth forests of the south (1, 2), and its presence in the north of the island at that time would be very unlikely as, by then, there were already no suitable forests left in the area.

The evidence suggesting the presence of a species of scops-owl on Príncipe was summarized, and a plea was made for birders visiting the island to make a special effort to find it (8). In 2016, Philippe Verbelen visited Príncipe, together with Felipe Spina (Fauna & Flora International / Fundação Príncipe), Bikegila and Sátiro da Costa and obtained the first evidence for the presence of a scops-owl on Príncipe: two rufous morph individuals were photographed on 4 July and 5 July in the area of Ribeira Porco after descending from the canopy in response to playback (3, 14, 4).

On May 2017, in that same area, one individual was captured by Hugo Pereira and Ceciliano do Bom Jesus to become the holotype (now stored at the Museu de História Natural e da Ciência da Universidade do Porto [MHNC-UP]). Recently, Melo et al. (1) confirmed the distinctiveness of the population of scops-owls from Príncipe using morphometrics, plumage coloration and pattern, song, and mitochondrial and nuclear DNA sequence data. After an extensive survey of the island was carried out, Freitas et al. (2) found that this species is restricted to the south of the island, inside the Príncipe Obô Natural Park, with most records being in lower altitude native forest. Its distribution strongly correlates with remoteness and land use, showing that it clearly depends on native forest. The estimated population size ranges from 1,149 to 1,597 individuals and it qualifies to the Critically Endangered category of the IUCN Red List (2).

Distribution of the Principe Scops-Owl - Range Map
  • Year-round
  • Migration
  • Breeding
  • Non-Breeding
Distribution of the Principe Scops-Owl

Recommended Citation

Freitas, B. and M. Melo (2023). Principe Scops-Owl (Otus bikegila), version 1.0. In Birds of the World (N. D. Sly, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.prisco1.01
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