First breeding record of the Barred Eagle-Owl in Singapore Island

This article documents the first confirmed breeding record of the Barred Eagle-Owl on mainland Singapore following the recent discovery of a juvenile. It explores the species' historical presence and describes efforts to study sexual dimorphism within the newly observed family group.

The Barred Eagle-Owl (Bubo sumatranus) is a relatively small eagle-owl that is found from southern Myanmar, Thailand, Malaysia, Singapore and southwards to Indonesia. Its natural habitat is subtropical or tropical moist lowland rainforests. It has also been reported in secondary growth, abandoned orchards, oil palm plantations and wooded gardens, showing its adaptability towards human encroachments. According to Wells, the Malaysian owls are in fact relatively unafraid of people. In Singapore, it is considered a rare resident species with breeding records only at Pulau Ubin (Ubin Island). In the main island of Singapore it was once considered an uncommon bird, but believed to have been extirpated since the mid 1920s. It was only in October 1996 that one owl was seen and heard at Bukit Timah Nature Reserve. Subsequently, sporadic sightings were also recorded at MacRitchie Reservoir and Nee Soon Swampforest. Recent sightings were at Bukit Timah Nature Reserve in 2015 and 2016. On 24th May, 2018, Peter Ding reported a pre-dawn sighting of an adult owl on a tree along the path to Singapore Quarry, next to Fuyong Estate. This was relatively near from what was believed to be its usual haunt at Bukit Timah Nature Reserve. Subsequent follow up search did not manage to locate this owl. However on 7th August, 2018, Peter Ding again sighted and recorded a video of what appeared to be a juvenile Barred Eagle-Owl calling for its parents at the same area. So the search was on again to locate the juvenile and its parents. The other interesting detail to follow up was to confirm the sexual dimorphism in this species as previously documented in Johor by Con Foley et al. Finally with that established, to hopefully determine the sex of the juvenile owl. In order to accomplish all these, clear photos were needed. At the time of discovery, the juvenile owl was estimated to be 8-10 months old, if the breeding cycle for this family was the same as the Johor birds. It was likely that the juvenile will soon disperse and the adults will start another breeding cycle towards the end of the year. Time was running out to locate it. Thankfully based on information from Peter, the activity and location of the juvenile were somewhat predictable, and the owl was seen and photographed on 8th, 9th, 15th, 16th and 17th August 2018. Underparts of the juvenile Barred Eagle-Owl Upperparts of the juvenile Barred Eagle-Owl In the above photos from 16th August, the juvenile owl is clearly seen to have almost finished moulting into adult-like feathers and features. Only part of the head and ear tufts remain whitish compared to the adults. Also notice that it’s clutching a bunch of leaves and acting like its a prey. The previous day, it was seen attempting to hunt next to a house. The juvenile on the left (based on facial and ear-tufts colour) and the adult male Barred Eagle-Owls. At this stage, the juvenile is almost full-sized In the above photo from the morning of 17th August, the juvenile can be seen with blood-smeared talons, so feeding was just completed, although it’s uncertain whether the food was self-caught or given by the adult. The juvenile was calling before it was found so it’s likely it was looking for its parents. At night, the juvenile was seen flying off with a snake, and again the adult was nearby. While all these were happening, the adult male had been spotted occasionally in the late evenings coming out of its daytime roost and flying off to the nearby trees to preen and prepare itself before starting its hunt at night. This presented another photo opportunity. The adult male Barred Eagle-Owl at a perch in the evening. This is a relaxed pose The adult male Barred Eagle-Owl on high alert, due to the calls of a family of Racket-tailed Drongos. Notice the elongated body and raised ear tufts A video of the adult make in fading light, showing its activity before nightfall. By the end of the video, it was hard to see the bird but it’s in fact becoming more active. Let’s move on to the identification of the adult male and female owls. It is known that Barred Eagle-Owls pair up and mate for life. So it should be possible to get both of them together in one photo to compare their size and appearance. One can speculate that if they are busy with caring for the juvenile, the chances of them being together side by side should be slimmer. It’s a busy time after all, having to feed a growing owl and teaching it how to fend for itself. On the other hand, if somehow the juvenile has just dispersed, the mating season should start again soon and the adults may spend more couple time together with displays of affection to reaffirm their bond. Display of affection of the adults Barred Eagle-Owls It is the female that initiate the display Remnants of feathers from a very recent kill on the talons of the owl. Photobombed by a planthopper The two photos below should help to answer the question of the sexual dimorphism of this species. Front profile of...