Philippine scops owl

The Philippine scops owl is a mid-sized species measuring around 23-28 cm and weighing around 200-300 grams.[3] A distinguishing feature of this owl is its large ears that are standing upright on its head. They also have big eyes that are dark in the center with a red/orange edge. In general, these owls are covered in dark brown feathers with dark streaks on them. Their ear tuffs also follow a similar pattern. Their forehead is whitish and they have a dark line around their facial disk.[2] There are three subspecies of Philippine scops owl which show three variations in morphology. The smallest morph, Otus megalotis nigrorum, has a reddish brown color, no scapular line, and no feathers on its upper feet. The medium-sized morph, Otus megalotis everetti, also lacks a scapular line and feathers on its upper feet but it has a more greyish brown color. Finally, Otus megalotis megalotis, is the largest of all three varieties and also has a grey brown color but it shows a scapular line and feathers on its upper feet. [3] Other morphological differences between the subspecies can be seen in the length of the tail, the wings, the culmen and the tarsus. These traits are longer in O. m. megalotis and are shorter in O. m. nigrorum.[6]

There are no significant difference in morphology between male and female Philippine scops owls although female scops owls tend to be larger in general.[6] The owlets however, present some contrast as they have fluffy rufous feathers. Once they reach the sub-adult age, they are black and greyish-white until they finally reach adulthood and turn brownish.[2]

The Philippine scops owl belongs to the Strigiformes order and the Strigidae family (typical owls).[3] The Strigidae family is the largest of the two families of owls and shows a great diversity, with species ranging from 40g to 40kg. Key features that distinguish owls of this family from their closest relatives (Tytonidae family) are their large eyes and the fact that their facial disk is circular and not heart-shaped. Otus megalotis species are then further classified into the Striginae subfamily according to skull morphology.[7] The Otus genus (scops owls) is one of the largest owl genera, counting approximately 50 species, yet these species are one of the smallest in size.[8] They are all found in the old world with the exception of one species, the Flammulated owl, which is found in North America. A distinguishing feature between this genus and other genera of the Striginae subfamily is vocalization.[8]

The Philippine scops owl is endemic to the Philippine Archipelago. This group of approximately 7,000 islands is prone to speciation and is a great location to study phylogeopgraphy. It was formed around 30-35 million years ago and lead to the evolution of different subspecies of Otus megalotis. The expansion and contraction of biomes during the last glaciation period as well as the profound topography in that area lead to isolation of individuals which eventually caused speciation.[6] There are seven Otus species in the Philippines, 5 of which are endemic to islands among the archipelago. These species include Otus longicornis, Otus mindorensis, Otus mirus, Otus magalotis and Otus fuliginosus. The other two species, Otus mantananensis and Otus elegans are not endemic to the Philippines. The three Otus megalotis subspecies are distributed among different islands of the Philippine Archipelago which suggests they could have evolved through speciation from geographic isolation. [6]

Rainforests, mature secondary woodland forests and forest edges are typical habitats in which Philippine scops owls can be found. They are mostly observed in the understory and rarely go above 1000m altitudes, with the exception of individuals which were reported on Mount Data, Luzon. [3] Researchers caught a Philippine scops owl in a net set up at 2m above ground during their study, which confirms that they are mostly understory arboreal species.[9]

Otus megalotis is endemic to the Philippine Archipelago but the three subspecies are distributed in different locations across the archipelago. O. m. megalotis species are found mostly in the northern Islands such as Luzon, Marinduque and Catanduanes. O. m. everetti species exist in the eastern and southern islands including Samar, Biliran, Leyte, Mindanao and Basilan. Finally, O. m. nigrorum species are endemic to Negros Island.[3] These owl species are not known to migrate and therefore have a limited distribution.[5]

Although they are classified as a species of Least Concern, habitat destruction from deforestation and fragmentation is a major threat to their population as they depend on forests for their survival.[5]

Philippine scops owls are sedentary birds with a limited home range. The fact that different subspecies are found on different islands limits intraspecific competition and allows these birds to have a smaller distribution where all the necessary resources are available.[3]