Ornithologists have discovered a new species of the scops-owl genus Otus inhabiting the forests of Príncipe Island, part of the Democratic Republic of São Tomé and Príncipe in Africa.
The Principe scops-owl (Otus bikegila) from Príncipe Island, Africa. Image credit: Philippe Verbelen.
Otus is a genus of scops-owls in the family Strigidae restricted to the Old World.
First introduced in 1769 by the Welsh naturalist Thomas Pennant, it is the largest genus of owls with over 50 species.
Members of the genus are colored in various brownish hues, sometimes with a lighter underside and/or face, which helps to camouflage them against the bark of trees. Some species are polymorphic, occurring in a grayish- and a reddish-brown morph.
These birds are small, with both sexes being compact in size and shape; females are usually larger than males.
“The discovery of a new bird species is always an occasion to celebrate and an opportunity to reach out to the general public on the subject of biodiversity,” said lead author Dr. Martim Melo from CIBIO and the Universidade do Porto and his colleagues.
“In this age of human-driven extinction, a major global effort should be undertaken to document what may soon not be anymore.”
“Birds are likely the best studied animal group. As such, the discovery of a new bird species in the 21st century underscores both the actuality of field-based explorations aiming at describing biodiversity, and how such curiosity-driven endeavor is more likely to succeed when coupled with local ecological knowledge, the participation of keen amateur naturalists, and persistence.”
The Principe scops-owl (Otus bikegila): an adult rufous morph (left) in the typical posture and an adult gray-brown morph (right) in a stress posture, when it raises the ear tufts to increase the efficiency of camouflage. Image credit: Marco N. Correia.
The newly-described species, named the Principe scops-owl (Otus bikegila), occurs at low elevations of the old-growth native forest of Príncipe Island, located in the Gulf of Guinea, approximately 220 km offshore Gabon.
The bird is currently restricted to the uninhabited southern part of the island but fully included within Príncipe Obô Natural Park.
“The discovery of a new species that is immediately evaluated as highly threatened illustrates well the current biodiversity predicament,” the researchers said.
“On a positive note, the area of occurrence of the Principe scops-owl is fully included within the Príncipe Obô Natural Park, which will hopefully help secure its protection.”
“Although it may seem odd for a bird species to remain undiscovered for science for so long on such a small island, this is by no means an isolated case when it comes to owls.”
The team’s phylogenetic analysis suggests that the Principe scops-owl descended from the first colonization of the Gulf of Guinea islands, being sister to the owl group including the mainland African scops-owl (Otus senegalensis), and the island endemics Sao Tome scops-owl (Otus hartlaubi) and Pemba scops-owl (Otus pembaensis).
The bird’s most diagnostic trait in the field is its unique call which, curiously, is most similar to a distantly related Otus species, the Sokoke scops-owl (Otus ireneae).
“Otus bikegila’s unique call is a short ‘tuu’ note repeated at a fast rate of about one note per second, reminiscent of insect calls. It is often emitted in duets, almost as soon as the night has fallen,” Dr. Melo said.
The new species occupies an area of about 15 km2, apparently due to a preference for lower elevations.
In this small area, the densities of the owl are relatively high, with the population estimated at around 1,000-1,500 individuals.
“We propose that the species is classified as Critically Endangered due to the small extent of occurrence, coupled with occurrence in a single location and inferred continuing declines in the extent of occurrence, area of occupancy, number of mature individuals and area, extent, and quality of habitat,” the scientists said.
“Effective conservation of the Principe scops-owl requires regular monitoring and further studies focusing on reproduction and potential nest predation by introduced mammals.”
“Widespread support for the conservation of the Natural Park is vital to ensure the protection of this species and the endemic-rich native forests of Príncipe on which it depends.”
The team’s findings appear in two papers in the journal ZooKeys and the journal Bird Conservation International.
M. Melo et al. 2022. A new species of scops-owl (Aves, Strigiformes, Strigidae, Otus) from Príncipe Island (Gulf of Guinea, Africa) and novel insights into the systematic affinities within Otus. ZooKeys 1126: 1-54; doi: 10.3897/zookeys.1126.87635
Bárbara Freitas et al. The recently discovered Principe Scops-owl is highly threatened: distribution, habitat associations, and population estimates. Bird Conservation International, published online October 31, 2022; doi: 10.1017/S0959270922000429