By The Sound Approach

Turkish Fish Owl

Turkish Fish OwlBubo semenowi, Akseki, Antalya, Turkey, 5 August 2009 (Arnoud B van den Berg). Walking after prey in river. Same first-year bird as in CD3-67 but silent and almost a month later.

When we started work on Undiscovered Owls, the Turkish Fish Owl Bubo semenowi, known to us at the time as ‘Brown Fish Owl B zeylonensis’, posed an enormous challenge. There had been just a handful of Western Palearctic records in the last 100 years, including two from its last known stronghold: southern Turkey. In late April 1990, a fisherman caught one alive on a hook near Adana (Magnin 1991). This became the only record for Turkey in the 20th century as the previous ones concerned birds collected in the late 19th century (Ebels 2002). Then in 2004 a participant in a survey of wildlife in the Antalya mountains photographed a pair at a secret location (Yöntem 2007).

With definite fish owls reported from locations around 300 km apart, we hoped that a viable population might still exist. Still, we were only half serious in spring 2009 when we asked Arnoud to go and find them. At first he was understandably reluctant. To ensure that the long road trip would be worthwhile, he and Cecilia took in several owls and other bird species along the way. Among others, they recorded Ural Owls Strix uralensis in Slovenia, Wallcreepers Tichodroma muraria in Bulgaria and Pallid Scops Owls Otus brucei in eastern Turkey. From there they headed west to the forests, cliffs and fast-flowing rivers of Mediterranean Turkey.

As they drove west along the south coast, they passed several interesting-looking valleys. None seemed to be quite right. They carried on to the Antalya area where Soner Bekir had suggested trying their luck. On their way to a town Soner had mentioned they crossed a river. The place looked ideal for fish owls with high, mature and dense deciduous trees standing in the clean water, and cliffs on either side. Better still, the river was full of fish and frogs, and easily accessible thanks to a good road on one side. If they could not find fish owls in this apparently ideal habitat, it would be hard to imagine finding them anywhere else. 20 June 2009 was a Saturday, and the valley was full of illegal fishermen. Almost all had left at dusk when a huge owl flew from the cliff to the river. It was only a silhouette. Arnoud could see no details of feathers, yellowish eyes or unfeathered legs, but was convinced it was not an eagle-owl. One reason was its late appearance; eagle-owls start flying a bit earlier. Another was its silence; eagle-owls seem to hoot for a few minutes before flying out most evenings, even in mid-summer.

Over the next three days, Arnoud and Cecilia searched the cliffs to look for nesting sites. At dusk they waited for the fish owl to show up, and at night they listened while camping along the river at a local fish restaurant, all in vain. However, they were encouraged by hearing the account of Ibrahim, the restaurant owner, who had lived most of his working life in Germany. About a year earlier, he had seen a huge owl sitting on a rock in the river at night. When it flew off, its wings were as long as his arms. Frustrated by the lack of further sightings, Arnoud and Cecilia decided to return in a few months, when they hoped that the owl would be hooting. On the way home they sent an email to Soner, telling him they had found a definite site but not managed to obtain photographs or sound recordings. 

Soner’s response was decisive. Within two weeks, on 2 July, he visited the same river with Murat Çuhadaroğlu. They had no luck at Arnoud and Cecilia’s spot, but carried on upstream, searching for eyeshine reflected in the light of their torch. Most was greenish and belonged to Wild Goats Capra aegagrus, but some 9 km further, orange eyeshine in the top of a pine on the other side of the roaring river stopped them in their tracks. A careful look produced much excitement when they realised it was a fish owl! Soner made some excellent photographs, proving beyond doubt that at least one individual was present. The next night, Soner’s friend Emin Yoğurtcuoğlu visited the same place and even saw two adults there. He also saw one closer to the location of Arnoud’s 20 June sighting. 

Arnoud and Cecilia went back a week later, this time by plane. Sleeping rough on the riverside near Soner’s tree, they not only had excellent views of both adults but also witnessed a newly fledged juvenile jumping from the cliffs into a pine tree top. This confirmed the species’ first documented nesting record in the WP. They visited this territory five times in all seasons within the next year (van den Berg et al 2009, 2010), collecting many photographs and sound recordings. Our knowledge of Turkish Fish Owl sounds grew exponentially, but the most important sound was still missing.

On Wednesday 17 March 2010, Mark and I arrived at Arnoud and Cecilia’s house in the Netherlands for a meeting. As we were catching up with each other’s news, Arnoud received a phone call from Soner and Emin, who we had employed to prospect for more fish owls. They had just become the first modern day birders to hear a fish owl hooting in the Western Palearctic, at a new site at a little lake in the Taurus mountains north of Adana. So no sooner had we arrived than Arnoud was preparing to leave. The next evening he arrived at Adana airport, where a car arranged for him by Soner and Emin was waiting. In the middle of the night, the site was difficult to find, and it was almost dawn when Soner finally talked him in. 

By day Soner and Emin showed him little piles of crab remains and pellets under old conifers, left behind by a fish owl, something they had also found underneath the previous year’s pine trees. Three friendly engineers working at the dam at one end of the lake told them that a shepherd had shot a huge owl a few years previously, which must have been the female. By the time of Arnoud’s visit the male had apparently not succeeded in attracting a new one, but at time of writing he has. In the evening, the engineers prepared a picnic. Arnoud’s participation came to an abrupt halt when he heard the male hooting in the distance. It carried on for much of the night, never quite where Arnoud hoped that it would be. Still, for a first ever recording of Turkish Fish Owl hooting, CD3-54 was not bad at all.

CD3-54: Turkish Fish Owl Bubo semenowi Mersin, Turkey, 19:52, 20 March 2010. Hooting of a male. Background: fast-flowing mountain streams. 100320.AB.195220.13

Oymapinar Baraji near Manavgat, east of Antalya, is a reservoir with steep banks of almost bare rock, on which by some miracle rugged woodlands of pine Pinus, cypress Cupressus and wild olive Olea europaea flourish. Its waters are vivid blue. For many summers, tourist boats have been taking people around the reservoir, thousands of them. One of the things the boatsmen show to their mostly Russian guests are some large owls that live near small caves in the cliffs, one pair in each of two canyons where rivers enter the lake. In June 2011, the Pilgaard family from Denmark sent photographs of the owls to a birder friend to ask what they were. The news spread quickly, and since then Oymapinar has become the place for anyone wanting to see Turkish Fish Owls.

Many birders have twitched the male in CD3-55 and its mate from boats, but Arnoud recorded it at night from a hiding place on the opposite crag. To get there he explored overgrown paths, squeezed through a narrow tunnel, and climbed dangerous rocks, several nights in a row. Before any of that he had to arrange permission from two authorities. It was a privilege, but one that he had earned.

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CD3-55: Turkish Fish Owl Bubo semenowi ‘Little Canyon’, Oymapinar Baraji, Antalya, Turkey, 23:45, 16 May 2012. On a snag atop a precipice, a male Turkish Fish Owl Bubo semenowi inflates his white throat and booms like a whale. Background: Levant Water Frog Pelophylax bedriagae, Eurasian Scops Owl Otus scops and Tawny Owl Strix aluco.120516.AB.234550.11

Habitat of Turkish Fish Owl Bubo semenowi, ‘Little Canyon’, Oymapinar Baraji, Antalya, Turkey, 23:45, 24 July 2012 (Dick Forsman). From peak at right, opposite from nest from vertical cliff, CD3-55 to 56 & CD3-60 were recorded.

Turkish Fish Owls have a very deep voice, too deep for many small speakers to reproduce. The loudest frequency in the hoot is around 170 Hz, putting Turkish Fish Owl in the same range as a Eurasian Bittern Botaurus stellaris, or about an octave lower than a male Eurasian Eagle-Owl. In the Western Palearctic, only Lapland Owl Strix lapponica sometimes produces even lower-pitched sounds. The hoots are not especially loud, but powerful and far-carrying. The torrential streams that thunder through most territories would drown out anything less. Not here. With a surface so calm, maybe even the fish can hear them.

At the time of writing, sound recordings of only three male Turkish Fish Owls are available to me. Arnoud recorded the two that you have heard, and José Luis Copete recorded the third. A recording of a fourth by Emin was sadly lost. Emin, Murat Bozdoğan and Soner also heard a fifth and sixth male while conducting our survey (Bekir et al 2010). Hooting of all six consisted of three or four notes repeated quickly.

Turkish Fish Owl Bubo semenowi, perched near nest, ‘Little Canyon’, Oymapinar Baraji, Antalya, Turkey, 17 May 2012 (Arnoud B van den Berg). One of the adults in CD3-56 & CD1-64 but a few days later, at dawn.

Amazingly, fish owl pairs often hoot in perfectly coordinated duets. In Turkey, Arnoud recorded duetting during three of the nights spent on the crag at Oymapinar Baraji, and José Luis Copete recorded an almost identical duet elsewhere. Male and female contributions are combined so smoothly and consistently, it seems hard to believe two owls could be involved. Nor is it obvious who is doing what. Listen carefully to CD3-56, however, and you’ll hear that the first four hoots up to the slight pause are exactly the same as in solo male hooting (it’s the same male as in CD3-55). The four higher-pitched hoots in the middle belong to the female, then the last four are from the male again. On one occasion, Arnoud recorded the complete male contribution to the duet – two sets of hoots and a gap between them – without the female (cf, CD3-56 at 1:22).

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CD3-56: Turkish Fish Owl Bubo semenowi ‘Little Canyon’, Oymapinar Baraji, Antalya, Turkey, 04:09, 18 May 2012. Hooting duet of male and female. Background: Eurasian Scops Owl Otus scops. 120518.AB.040900.12

Up to now we have never been able to see a pair of Turkish Fish Owls while they were hooting. Comparing the size of the owls (females are slightly larger) and watching them inflating their pale throat ‘badges’ would soon confirm who did what, if only we had the opportunity. Instead, we have sexed their duets by focusing on the lower-pitched individual. Since that bird always starts the duet and is the only one we have ever heard hooting solo, we conclude that it must be the male. In Blakiston’s Fish Owl B blakistoni too, the male is the one that starts the duet and hoots solo more often than the female. Occasionally the order is reversed in both insular nominate blakistoni and continental subspecies doerriesi, especially when agitated (Brazil & Yamamoto 1989, Jonathan Slaght pers comm). 

Turkish Fish Owl once occurred all the way from Turkey to Pakistan. Pleistocene remains have also been found on the island of Crete (Weesie 1988) but the species is not known from further west (cf Louchart 2011). Away from Turkey, the only records in the past 100 years were in Israel, where it became extinct in August 1975 (Ebels 2002), and Iran, where the first pair for up to a century was found in Hormozgan province on 18 January 2004 (van Diek et al 2004). It has subsequently been recorded in two other Iranian provinces (Khaleghizadeh et al 2011). Originally semenowi, as Turkish is known to taxonomists, was described as a species (Zarudny 1905), based on a holotype from Khuzestan, western Iran. Subsequently, however, it has usually been considered one of four subspecies of ‘Brown Fish Owl’ Bubo zeylonensis, the others being nominate zeylonensis (based on a type specimen from Sri Lanka), leschenaulti (type specimen from Chandranagore, north-eastern India), and orientalis (type specimen from Dakto, modern day Vietnam). 

Very few recordings of ‘Brown Fish Owl’ have ever been published, and the identity of some is debatable (Robb 2009, Chappuis 2010). Of the ones we trust, all are from India eastwards and all sound very different from what Arnoud has recorded in Turkey. In January 2013, Arnoud and Cecilia went to India to investigate.

In Goa, Arnoud learned about a river with at least four pairs of fish owls, along a quiet dead end road near a camp where birders can stay. Leio de Souza showed him and Cecilia large boulders with cracked crab shells, indicating where fish owls fed. They were much shier than their Turkish counterparts, and flew away immediately when humans arrived. Prolonged views like Arnoud and Cecilia had enjoyed in Turkey eluded them. Only by leaving equipment in promising spots and walking away was it possible to record the owls up close. In CD3-57, you can hear a male Brown Fish Owl from Goa hooting solo on a background of clicking frogs. 

In CD3-58, a pair starts duetting after a few introductory hoots. As in Turkish Fish Owl, we believe that the male is responsible for the first and last parts, in this case single hoots, while the female produces the middle part. At first the female is lower than the male, but she gradually rises in pitch until she is almost level. Then in a second series the female is higher-pitched than the male, the normal state of affairs. In CD3-59, you can hear a duet in which the same male and female were perched some distance apart, separating the components of the duet in space.

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CD3-57: Brown Fish Owl Bubo zeylonensis Bhagwan Mahaveer Wildlife Sanctuary, Goa, India, 21:07, 11 January 2013. Hooting of a male. Background: clicking sounds of frogs. 130111.AB.210700.01vv

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CD3-58: Brown Fish Owl Bubo zeylonensis Bhagwan Mahaveer Wildlife Sanctuary, Goa, India, 19:02, 15 January 2013. Hooting duet of a pair. 130115.AB.190204.02

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CD3-59: Brown Fish Owl Bubo zeylonensis Bhagwan Mahaveer Wildlife Sanctuary, Goa, India, 06:21, 15 January 2013. Hooting duet of male and female, separated in stereo image. The male is more distant and the female is perched closer by to its right. By the end, the female has flown to join the male. This recording shows clearly that authors such as Legge (1880) and Shashidara (1989) were wrong when they wrote that in duets, one bird gives the first and another the second and third hoots. 130115.AB.062100.11

We know of three-hoot duets like this from several places in western and central India, and from Sri Lanka. In Turkish Fish Owl, no such three-hoot duet exists. The nearest thing we have heard was when Arnoud recorded a single strophe of a slow form of hooting. This consisted of five notes, possibly produced by just one individual (CD3-60). Every other time, hooting of semenowi sounded three to four times faster than that of zeylonensis.

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CD3-60: Turkish Fish Owl Bubo semenowi ‘Little Canyon’, Oymapinar Baraji, Antalya, Turkey, 04:26, 13 May 2012. Slow hooting, probably of a male. Background: Levant Water Frog Pelophylax bedriagae and Eurasian Scops Owl Otus scops. 120513.AB.042600.02

In south-eastern Asia, ‘Brown Fish Owls’ sound different again. In this third vocally defined population, each strophe is a quick double hoot. When male and female duet, this gives six note duets (CD3-61): two male then two higher female then two male hoots (Brazil & Yamamoto 1989). Arnoud played recordings from both of the other two ‘hoot-types’ to adult Turkish Fish Owls at close range several times in Turkey, and they never showed even the slightest interest. If further sound recordings confirm the differences described above, and other lines of evidence point the same way, a three-way split seems likely.

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CD3-61: Bengal Fish Owl Bubo leschenaulti Huai Kha Khaeng reserve, Uthai Thani, Thailand, April. Hooting duet of a male and female. Roland Eve.

Provisionally, I suggest that B leschenaulti would be the correct name for the third, south-eastern species with the double hoot. Recordings attest to its presence from south-eastern Asia and as far northwest as Tangail in Bangladesh. Tangail is only 250 km east of Chandannagar, the type location of leschenaulti. Because of the 250 km gap, there is still some room for doubt. Sound recordings from Chandannagar might help, or alternatively genetic evidence linking the type specimen with double hooters from further east but not with single hooters from further west. Let’s call this provisional south-eastern species Bengal Fish Owl in honour of the type location, and assume that orientalis is its darker north-eastern subspecies. 

So far we know very little about the phenology of hooting in Turkish Fish Owl. All we know is that hooting has been reported in March to early April, which is the courtship period, in mid-May when there were young in the nest, and in late June when the young had already fledged. Looking to the Far East, Blakiston’s Fish Owl may offer some clues about what more we might expect. Japanese blakistoni hoots every month of the year with a peak in late February to March, just before egg-laying, and regularly until June. It hoots much less frequently from November to early February (Brazil & Yamamoto 1989). Russian doerriesi duets most frequently in February and March, and continues at least until the young fledge in late May. Second calendar-year birds start hooting only in May. Their duets are weaker and less regular than those of adults, but can be heard as pair-formation takes place throughout the summer and autumn months (Pukinskiy 1974, 1993).

Localities of Turkish Fish Owl Bubo semenowi in 1915-2014 (green) and very approximate breeding distribution of Brown Fish Owl B zeylonensis (purple) and Bengal Fish Owl B leschenaulti (orange) , based on recordings from own collection, online collections and commercially available publications. Recording locations indicated by red dots.

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