Rajah Scops Owl rediscovered in Borneo
By Gege Li on May 5th, 2021
Steeped in natural history, the island of Borneo is a hub of biodiversity that comprises three countries. Its rainforests are estimated to be 130 million years old – double the lifespan of the Amazon – providing a home to thousands of different plant and animal species. The Rajah Scops Owl, a species native to southeast Asia, is one such resident. There are two subspecies of the owl: the Otus brookii solokensis found in Sumatra and the far more elusive Otus brookii brookii of Borneo.
Though the Sumatran subspecies is well documented, almost 130 years have passed since O. brookii brookii, the Bornean subspecies, has been officially sighted. It was first recorded in Sarawak in northwest Borneo in 1892 and in that time, the subspecies has seemingly vanished off the face of the Earth. But an unexpected discovery confirming the existence of O. brookii brookii has sparked new interest in finding the owl again.
A rare look
In 2009 a team, led by Thomas Martin and including avian ecologist Andy Boyce, began observing birds and searching for nests in and around Kinabalu Park in Sabah, a Malaysian state in Borneo, as part of a decade-long project. A year in, on May 4, 2016, one member of the group, Keegan Tranquillo, came across an owl which looked distinctly different to others on the site, and quickly alerted Boyce to the unusual individual.
“I was pretty convinced immediately that it was a [Rajah Scops Owl],” says Boyce, who is currently an ecologist at the Smithsonian Conservation Biology Institute. “I knew of the owl, I knew that there was a possibility that it should occur somewhere on Mount Kinabalu, but there was no concerted effort to survey specifically for this bird.”
The owl was found roosting about a meter above the ground near a small bank. Boyce and his colleagues made the most of the rare opportunity, snapping as many photos of the individual as they could – the first ever images of O. brookii brookii. Though it may be notoriously difficult to find, once spotted, it is relatively easy to distinguish it from the Mountain Scops Owl that is common in the region, says Boyce. The Rajah species is larger in size and has distinctly orange irises, as well as the small ear tufts characteristic of Scops Owls in general. It also has a speckled brown and black crown.
What’s more, compared to its Sumatran counterpart, O. brookii brookii varies in several ways, raising the possibility that the two subspecies could in fact be entirely separate species. Each has distinct plumage colors and patterns and notably, are found on different islands. This geographical separation favors each population’s potential evolution into different species, and Scops Owls have been known to diverge following isolation in the past.
“In all likelihood, this is probably a separate species given what we know about the biogeography of small owls in that part of the world,” says Boyce. “But we’ve been totally unable to address that using modern methods because there’s been no contact with the bird.”
The team were mindful of keeping their distance from the owl so as to avoid disturbing it, in the hope that it might return to the same spot in the future so they could learn more about the bird. Unfortunately, the owl wasn’t seen again, even after several more visits to the roosting area. Boyce also made a further ten trips to keep an ear out for nocturnal calls, but to no avail.
He says he would’ve loved the opportunity “to be able to document its song, document a nest, find more individuals at the site, but we’ve just basically gotten this very quick, tantalizing view.”
It’s possible that the one-off sighting means numbers of O. brookii brookii are low in the wild. Given its reliance on mature forests, many of which are at risk of deforestation in Borneo, the survival of this owl may well be under threat. It could also be that the discovered individual had strayed from its main range, which might explain why it was only seen once.
“One possibility is that it usually occurs at slightly lower elevations and this individual wandered up to this particular area,” says American Bird Conservancy’s John Mittermeier, director of its threatened species outreach, who is working with Re:wild and other partners to get confirmed sightings of about 150 species of lost birds.
Because we still know so little about it, the sighting of this elusive owl only makes further searches in the area all the more necessary. Being unable to ever observe it, conservationists and researchers don’t know what its vocalizations sound like, and aren’t able to elucidate much about its ecology and habitat other than that it lives in montane forests.
Finding another individual or population is therefore critical for shedding light on the virtually unknown Bornean Rajah Scops Owl. Ideally, future sightings will also allow researchers to take blood or feather samples to analyze whether O. brookii brookii should be classified as a different species from their relatives in Sumatra, as well as carry out a comprehensive study of its physical characteristics and behavior. Not only will that make it easier to compare it with other Scops Owls, it means that we have a clearer outlook on how we can protect the species.
It’s a shame we have so little information, says Boyce. “We don’t know anything about the animal… Its preferred habitat will have major consequences for the type of conservation actions that might be necessary.”
Luckily, one key way to shed light on the Rajah Scops Owl’s whereabouts and habits is simply to continue to ask local people ,because it’s always possible that someone may spot the owl. The research team surveying birds in Borneo had asked local birders, biologists and others working with them if they had ever seen the bird before, but no one recognized it. Boyce points out that though this rediscovery marks only the second documented sighting of the owl, it’s quite possible that people living in Sabah and other regions of Borneo have seen it before – and even know of some of the spots it frequents.
Rediscoveries like this are important for finding and protecting species, but also getting them on people’s radar to raise awareness and fuel engagement with forgotten or little-known animals and plants.
“One thing I think is a hugely important aspect of these rediscoveries of lost birds is the excitement and interest they generate,” says Mittermeier. “The idea that there’s a mysterious species out there that no one can find at the moment should be a call to action for birdwatchers in the area, and it’s a way of getting people excited to search new areas and help make discoveries.”
“In some ways [it’s] really nice to be reminded that there’s a lot out there still to discover that we don’t know, that we don’t fully have our hands around. This bird potentially going missing then showing back up is a reminder of that,” says Boyce.
Gege Li is a freelance science writer based in London, UK and was previously an intern at both New Scientist and Chemistry World magazine. Though her background is in biochemistry, she is also passionate about writing about wildlife, the environment, health and technology, to communicate important scientific research and ideas to the public.