Lost Birds
© Birds of the World | Cornell Lab of Ornithology [Ian Willis]

Siau Scops-Owl

Otus siaoensis


Owls (Strigidae)



(157 years)




Critically Endangered


Endemic to the tiny volcanic island of Siau (Indonesia), just to the north of Sulawesi. The only evidence of this recently elevated species is a single specimen collected in 1866, making this one of our longest lost birds (>150 years). The voice, therefore, is unknown, although it likely sounds similar to the whistled calls of scops-owls on nearby Sangihe and Sulawesi.

Last Documented

Known from only a single specimen, which was collected on the small island of Siau, Indonesia, in 1866 (RMNH 88345).

Rijksmuseum van Natuurlijke Historie (Naturalis Biodiversity Center), Netherlands.

Page Editors

  • Cameron Rutt
  • Search for Lost Birds

Species News

  • An expedition is preparing to search for an owl that hasn’t been seen in more than a century

    Cameron Rutt / 5 Jul 2023

    Siau Island in North Sulawesi, Indonesia is small–only 20 kilometers around. Despite its petite size, Siau could still be holding some secrets. Mount Karangetang (also known as Api Siau) on the north side of the island reaches nearly 6,000 feet (1,827 meters) at its highest point. The upper elevations of the volcano, which is still active, are under-explored. But an expedition team with the local Indonesian Forest Management unit, Burung Indonesia, a bird conservation organization and partner of BirdLife International, and a local guide, is setting out to survey the island in late October and early November to see if they can find traces of a bird that has been lost to science since 1866: the Siau Scops-owl.

    “It is a bit of an unknown really, what could be high up on Siau,” says James Eaton, who is working with Burung on the expedition. “If you look on Google maps, the volcano has sulfur and cloud above it, with lots of old lava trails coming down, but it still looks like there’s a little forest around the top.”

    Siau is part of the Wallacea Biodiversity Hotspot, a region home to more than 270 species of birds found nowhere else on Earth, and the island itself has been identified as an Important Bird Area and an Alliance for Zero Extinction site, making it one of the highest priority sites in the world for biodiversity conservation. 

    The one and only documented record of a Siau scops-owl was 156 years ago, when a single individual was found by a Dutch collector visiting Siau in 1866. The only information ornithologists have about the owl, which is about five sentences, is from that original specimen.

    Although there haven’t been any other confirmed sightings of the owl, the Siau scops-owl has not been forgotten. The bird is one of the top 10 most wanted birds by the Search for Lost Birds, a collaboration between American Bird Conservancy, BirdLife International and Re:wild launched in 2021. And there have been occasional reports of owls on Siau, which have given ornithologists hope that the owl could be hiding  in forest patches on the island. In addition to reports of a call that sounds like an owl, there are anecdotal reports of sightings that potentially match the Siau Scops-owl. 

    A video in 2017 of an owl on Siau was the most recent glimmer of hope that the species may have finally been rediscovered.

    “There was a video of a bird captured by the local community inside a building, but the video sparked a discussion about whether it was actually the Siau Scops-owl that we have been looking for so many years,” says Adi Widyanto, head of conservation and development with Burung. “Some say ‘yes,’ but some doubt it to be the one that we are looking for. There is no conclusion about whether it was Siau Scops-owl.”

    Recent rediscoveries of other rare Indonesian birds have made the expedition team hopeful. In 2021, the Borean subspecies of the Rajah Scops-owl was rediscovered after nearly 130 years. The Black-browed babbler has a similar history to the Siau Scops-owl. The babbler had only ever been documented once, when it was originally described, but was unexpectedly rediscovered more than 170 years later.

    Much of Siau’s forests were destroyed under Dutch colonial rule for plantations to grow cloves, nutmeg and coconut. The patches of forest that remain are small, but they could be enough for the Siau Scops-owl. 

    Other species of scops-owl have been able to adapt to dramatically changed landscapes, which is yet another reason why ornithologists and conservationists are reluctant to stop searching. 

    Local communities and government on Siau are slowly recovering parts of the island. They have converted former agricultural areas and plantations into agroforestry areas.

    “Scops-owl are very rare in plantations,” explains Ganjar Cahyo Aprianto, conservation program officer with Burung. “But we have found them [on Sangihe Island] on the forest edge and near the forest edge.” 

    On Sangihe, recovering forest fragments offer shelter for a number of endemic bird species including a scops-owl, the Sangihe scops-owl. 

    “On a lot of the slopes on Sangihe, there's quite a lot of good regeneration,” says Eaton. “Quite a few of the endemic birds  are moving into areas where previously they had long gone. I can imagine that would be the same on Siau as well.”

    The expedition team thinks several scenarios could be possible concerning the whereabouts of the Siau Scops-owl. 

    “This scops-owl may have just disappeared close to villages,” says Ferry Hasudungan, conservation program coordinator for Sangihe Island with Burung. “Or maybe the owl has a breeding area in the natural forest and moved out of the area nearest the plantations.”

    The last comprehensive survey of Siau was in 1995, and although the survey covered much of the island, researchers didn’t venture higher than 1,150 feet (350 meters). This time, the search team is targeting three areas between 1,950 and 2,600 feet (600 to 800 meters). They’ll stay at each sight for two nights, searching for any owls with spotlights and recording equipment. 

    Scops-owls are nocturnal, and their most active hunting times are at dusk and dawn. The search team, which includes the island’s forest management unit, plans to visit each forest plot at night. In addition to listening for calls, the team will play recordings of related scops-owl species in hopes of getting a response. If they do, they will try to catch the owl answering the call in the light of their headlamps or spot it with a thermal imaging scope. The definitive proof they will need to officially rediscover the species will be a photo, or an unmistakable sound recording which researchers are confident could not have been made by any other owl. 

    The weather will be the biggest challenge the team has to contend with. This year has been a La Niña year, and it rained every day from June to October. If the rains don’t subside, it will be too wet and difficult to search the forests at night.

    “​​The meteorological office predicted at the beginning of the year that the dry season will be somewhat wet,” says Ferry Hasudungan. 

    But a break in the weather came in September and the expedition team hopes it will stay.

    The search for the scops-owl on Siau builds on conservation work by Burung Indonesia on the neighboring island of Sangihe. Sangihe is home to several endemic and threatened species. Burung and its government partners are leading a six-year monitoring program on the island to better understand the populations of several of them.  

    In 2020, they completed a baseline survey of the birds living in high-quality habitat on Sangihe. Their results were promising and they even managed to catch a glimpse of a possible Sangihe White-eye, another lost bird species. The white-eye is Critically Endangered and has only been spotted four times since it was described by science with the last documented record in the late 1990s. 

    Following the baseline surveys, Burung and local government partners are working with local communities on Sangihe to protect forested areas that are home to rare species like the Sangihe White-eye, Sangihe Whistler, and Sangihe Golden-Bulbul. Together Burung, the government, and communities have implemented patrols and eliminated habitat disturbances. 

    “We’re starting to see even rare animals recolonize the habitats,” says Adi Widyanto, with Burung.

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