The Migration Highway Above the Bosphorus, Birdwatching in Istanbul

Istanbul is not only where two continents meet; it is also one of the most important crossing points in the world for birds. According to migration studies carried out in the city, every spring and autumn around 400,000 storks, 200,000 birds of prey and hundreds of thousands of songbirds, waterbirds and shorebirds pass over different parts of Istanbul. Most of this traffic flows overhead without anyone noticing.

This article is about how to see it. It explains why birds choose the Bosphorus in particular, which species pass in which months, where to watch from in spring and in autumn, how the counts are carried out, which visitors arrive at the wetlands in winter and which birds live in the city all year round. At the end you will find practical advice, from choosing binoculars to birding ethics, and plans for two different migration days.

Why the Bosphorus

Large birds such as storks, eagles and buzzards make their long journeys mostly by soaring rather than flapping. They circle upwards in the warm air currents that rise from sun-heated land, then glide without flapping to the next one. As Zeynel Arslangündoğdu puts it, this is the logic of covering the greatest distance for the least energy. Because these currents do not form over the sea, soaring birds avoid wide stretches of water and choose narrow crossings where land masses come closest together. The Bosphorus, about 30 kilometres long as the crow flies, is one of the most important bottlenecks of this kind in the world.

Turkey has three great crossings for soaring birds: the Bosphorus in the northwest, Borçka in Artvin in the northeast, and the Belen Pass in Hatay in the south. Birds setting out from Central and Eastern Europe cross into Asia over the Bosphorus in autumn and use the same route in reverse in spring. Songbirds, shorebirds and many waterbirds, on the other hand, migrate by flapping flight and can cross seas directly; for them Istanbul's northern forests, pastures and wetlands are resting stops.

Who Is Up There

Storks head the list. According to a study published in the journal Sandgrouse, the entire eastern population of white storks, more than 340,000 birds, flies over the Bosphorus. The highest autumn count of white storks at the Bosphorus is 210,000 in 1971; for the black stork the record is 17,000 in 2008.

For birds of prey the importance of the Bosphorus is even more striking. Most of the world population of lesser spotted eagles and Levant sparrowhawks crosses into Asia over the Bosphorus, at least in autumn. Autumn counts have recorded high numbers such as 26,000 honey buzzards (1971), 80,000 common buzzards (2008), 4,600 short-toed snake eagles (2008) and 2,700 black kites (1971). A short but wide-ranging multi-station survey in 2008 showed that more than 150,000 raptors use the area in autumn.

Rarer species also pass among these great flocks. A spring count by the Istanbul Metropolitan Municipality singled out the Egyptian vulture, the greater spotted eagle and the eastern imperial eagle as threatened species; the same count also recorded common buzzard, lesser spotted eagle, booted eagle, black kite, short-toed snake eagle, goshawk, marsh harrier, falcons and sparrowhawk. Alongside the white storks, black storks and great white pelicans are also among the soaring migrants.

Spring Migration, March to May

The spring migration of soaring birds peaks in March, April and May and is best watched from the Sarıyer ridges on the European side of the Bosphorus. The reason is geography: the Black Sea stands like a barrier in front of birds heading north, and the prevailing northeasterly winds gather them over the northernmost 10 kilometres or so of the strait. The forests and natural areas of the north also allow birds to rest and stop over here.

The most detailed record of this season comes from spring 2006. In a study published in Sandgrouse, in which members of the Istanbul Birdwatching Society took part as observers, birds were counted from a single point for 72 days between 18 March and 31 May, and a total of 100,051 soaring birds were recorded. Of these, 51,958 were white storks, 16,185 common buzzards, 15,232 lesser spotted eagles and 9,085 honey buzzards. The count point was at Keskin Viraj on the road between Sarıyer and Rumeli Feneri, about 950 metres east of the entrance to Koç University, at 182 metres above sea level. Local birdwatchers had known it as the best spring site since the 1990s.

The same study also shows the calendar of each species, which helps when choosing your day.

• White stork: The peak came at the end of March; 9,569 storks passed on 25 and 26 March combined. Migration had begun before the study started and continued into June.
• Black stork: The busiest day was 25 March, with 207 birds.
• Lesser spotted eagle: It peaked at the end of March; 3,673 birds were counted on 31 March alone.
• Short-toed snake eagle: Most passed in late March; the busiest day was 26 March.
• Eurasian sparrowhawk: Passage was heaviest in late March and April, peaking at 125 birds on 2 April.
• Honey buzzard: One of the latest to arrive. The first were seen on 12 April, the main passage began after 30 April and it peaked with 1,185 birds on 12 May.
• Hen harrier: 92 birds were recorded; the researchers note that this is by far the largest total from any watch point in the Middle East in either season.

The birds' behaviour at this point makes watching easier. Having crossed the water to the European shore, they arrive low, having lost height. Those arriving north of the count point turn south to glide along the hillside and use the thermals on the slopes; they then enter the Rumelikavağı valley, gain height quickly in its strong thermals and leave towards the flatter country in the direction of Lake Terkos. Most white storks, however, pass about 5 kilometres further north, along the line between Poyrazköy on the Asian side and Garipçe on the European side.

Today the municipality's Feneryolu Keskin Viraj Bird Observation Tower stands in this area. Under the project "Istanbul's Migratory Raptors Are Protected", run jointly by the municipality's Parks and Gardens Department and WWF Turkey, counts are held twice a year, in spring and autumn. The spring leg of one of these counts took place at this tower from 1 to 5 April; together with 7,707 raptors of 17 species, white storks, black storks and great white pelicans were counted, bringing the total to 21,113 migrating birds. The tower is described as one of the best places in Europe to watch spring migration, with 36 soaring species recorded there.

Autumn Migration, August to October

In autumn the migration of soaring birds peaks in August, September and October, and this time the stage is the Asian side. Sources say autumn migration is best watched from the Küçük Çamlıca and Büyük Çamlıca hills; the Beykoz ridges and, in recent years, Toygar Tepe are also mentioned. Migration studies carried out at Çamlıca by foreign researchers, especially in the 1970s, left a lasting mark on the field. As autumn migration has become better known, Büyük Çamlıca now draws many visiting birdwatchers.

At 262 metres above sea level, Büyük Çamlıca is best for birding in September and October. The species seen most often here are honey buzzard, black stork, short-toed snake eagle, black kite and Levant sparrowhawk, with lesser spotted eagle, hobby, booted eagle, sparrowhawk and white stork also on the list. Migration watching events are held in Büyük Çamlıca Grove, and the municipality and WWF Turkey planned their autumn count there for 20 September to 10 October.

The Levant sparrowhawk deserves a separate note. The migration of this small raptor is squeezed into a very short window in both spring and autumn. In spring 2006 only 16 Levant sparrowhawks were counted over the Bosphorus, whereas thousands pass every autumn. So if you want to see one, the place is Çamlıca and the season is autumn.

Storks cross the Sea of Marmara by a different route from the raptors. In autumn some of the flocks that reach Silivri and Büyükçekmece try to cross the sea from there. The rest follow the northern shore of the Marmara and cross to the Asian side over the historic peninsula. There the route divides again: some flocks cross the sea via the Princes' Islands, while others go round the Gulf of İzmit and head south.

That is why in autumn you can see stork flocks not only from the hills but from inside the city as well. Sources say that storks mostly try to cross the Marmara over Büyükçekmece, Küçükçekmece, Yeşilköy, Zeytinburnu, Eminönü and the Islands, and that the hills of Büyükçekmece are an important stopover on their way to Africa. During the autumn passage, on a clear day's walk along the shore, simply looking up may be enough.

A Counting Tradition of a Century and a Half

Regular observation of bird migration over the Bosphorus goes back to the middle of the 19th century, to the observations of raptors and storks by Amédée Alléon and Jules Vian published in 1869. They were followed by researchers such as Steinfatt in the 1930s, Nisbet and Smout in the 1950s and Porter and Willis in the 1960s; the whole autumn season was first counted in 1966. Spring counts began with Mauve in the 1930s and continued at various points in Büyükdere, Sarıyer and along the Rumeli Feneri road. Research that long focused on autumn has in recent years been balanced by spring studies.

Understanding migration itself took a long time. Aristotle believed that some birds hibernated or turned into other species. The most striking proof came in 1822 from a stork shot in Germany: an arrow of Central African origin was lodged in its neck, and naturalists concluded that the bird had travelled thousands of kilometres. In 1906 people began fitting rings to storks' legs, which is how it was learned that they winter south of the Sahara.

Today the counting tradition continues with volunteers and institutions. The Wildlife Unit of the municipality's Urban Ecological Systems Directorate organises the spring and autumn counts. Alongside the birds, weather data such as temperature, wind, pressure and humidity are recorded every hour, because these conditions directly affect raptor migration.

Winter Guests at the Wetlands

Migration does not happen only in spring and autumn. For waterbirds the busy periods are the start and end of winter. The numbers of ducks, grebes, herons and cormorants rise noticeably in winter with migrants from the north; some shorebirds also arrive at Istanbul's wetlands as the north turns cold, while others stop only briefly to feed and rest. To see these birds you need to head for the city's lagoon lakes.

• Lake Küçükçekmece: A lagoon at sea level on the western side of the city, separated from the sea by a spit of sand and gravel. Seawater enters through the outlet at its eastern end, so the water is somewhat salty; the Nakkaş, Sazlıdere and Eşkinoz streams flow in from the north.
• Lake Büyükçekmece: A lagoon separated from the sea by a barrier crossed by the historic Kanuni Sultan Süleyman Bridge, now used as a drinking water reservoir. Between the dam and the sea there is a slightly salty lake, small pools and reed beds. The first two phases of the Nature Park on the lakeshore opened to the public on 14 March 2024, and the project includes birdwatching points.
• Kamil Abduş Lake: A lagoon of about 300 hectares on the Tuzla shore, used as a salt pan until 1929. The lake dried out completely in 2001 and was rescued by deepening its bed and reopening its connection to the sea; artificial islets were built for birds to rest and breed. It fits easily into a day in Tuzla.

The City's Own Birds

You do not need to travel far to watch birds outside the migration seasons. A ferry ride, a walk in a park or breakfast by the shore can be enough.

Shearwaters are the Bosphorus's own birds. If, from a ferry, you see flocks flying fast just above the water, wingtips almost touching the surface, showing dark backs and white bellies in turn as they tilt from side to side, you are most probably watching yelkouan shearwaters. Even the species' scientific name comes from the Bosphorus: the Italian naturalist Giuseppe Acerbi described it in 1827 from specimens collected there and carried the Turkish word "yelkovan" into its scientific name, Puffinus yelkouan. Arslangündoğdu notes that it is still not known whether shearwaters breed in Istanbul.

Cormorants are the quiet residents of the shores and piers. Istanbul has both resident cormorants and winter migrants; these birds make shorter movements rather than long migrations. The most familiar birds of the shore, though, are the gulls. Large gulls such as the yellow-legged gull, which also breeds in Turkey, are opportunistic feeders: they search rubbish tips and shorelines for food and sometimes rob smaller gulls and seabirds of their catch.

The shrill calls heard in parks in recent years belong to green parakeets. The rose-ringed parakeet is native to South Asia and the Sahel belt of Africa; birds brought in as pets that escaped or were released have established permanent populations in Istanbul, as in many European cities. Sources speak of more than a thousand birds in Istanbul, with colonies concentrated in parks; the species is regarded as invasive and has been recorded in 22 Turkish provinces. Its larger relative, the Alexandrine parakeet, has also formed feral populations in Turkey.

Songbirds are an important part of migration too, they are simply less conspicuous. Swallows, wagtails, thrushes, reed warblers, warblers, flycatchers and finches pass through Istanbul by flapping flight, stopping in suitable habitats along the way. Some songbirds can more than double their normal weight before migrating, and swallows can cover a thousand kilometres or more a day. In spring they shorten their stopovers to reach their breeding grounds early, which is why spring migration passes more quickly than autumn migration.

Reading a Migration Day

Migration does not run to a timetable; on one day of a given week thousands of birds may pass, and the next the sky may be almost empty. Knowing a few things improves your chances.

• Season: For soaring birds, aim for March, April and May in spring and August, September and October in autumn. In spring, late March stands out for storks and lesser spotted eagles and the first half of May for honey buzzards; in autumn, September and October are the months for Çamlıca.
• Time of day: Because soaring birds depend on warm air rising from the land, do not expect heavy passage before the sun has warmed the ground. In the 2006 spring count observers counted daily between 09.30 and 17.30.
• Wind: Sources note that the prevailing northeasterly winds gather the birds over the northern Bosphorus. In spring 2006 the wind blew from the north on 52 of 75 days and from the south and southwest on 23; wind speed was highest between 09.00 and 16.00.
• Changing weather: Spring in Istanbul is wetter and cloudier than autumn, and conditions can change suddenly. When the wind turned from north to south, temperatures were recorded rising by as much as 10 degrees. Visibility drops on misty days, although in 2006 it generally remained adequate.

Binoculars, Field Guides and Record Keeping

• Binoculars: Most observers in the 2006 count used 8x or 10x binoculars. For a beginner, a light pair at one of these magnifications that you can hold comfortably for long periods is enough.
• Telescope: A 20x60 telescope was kept ready throughout the same count. At Çamlıca and at the Sarıyer tower a telescope helps to pick out distant soaring eagles.
• Camera: In 2006 cameras helped with identifying eagles and harriers in particular. Photographing a bird you cannot identify and comparing it with a guide later is a good method. Remember that a greater spotted eagle can slip past even experienced eyes among the crowds of lesser spotted eagles.
• Field guide: The Birds of Prey Guide published by the municipality's Parks, Gardens and Green Spaces Department is a local starting point for the raptors seen in Istanbul.
• Record keeping: Recording your sightings contributes to science. eBird, launched in 2002 by the Cornell Lab of Ornithology and the National Audubon Society and covering the whole world since 2010, is a database that brings volunteer observations together; the data are used to define migration routes and to track how climate change affects where birds live. Trakus, where observers in Turkey share photographs and records, is also a community platform where you can ask for help with identification.

Birding Ethics

According to the municipality's wildlife unit, birds of prey today face threats such as habitat loss, vehicle collisions, gunshot wounds, poisoning and the smuggling of chicks and eggs. Birds on migration routes are already travelling at the limit of their energy. The observer's job is not to add another item to that list.

• Do not approach nests, roosting trees or resting flocks; good birding is done from a distance.
• Do not call birds in with recorded sounds, do not use flash and do not try to flush a bird for a photograph.
• At wetlands, stay on the paths and at the viewing points; reed beds are shelter and breeding grounds for many birds.
• In protected areas such as the Feneryolu Wildlife Development Area in Sarıyer, follow the rules, leave no litter and do not pick plants.
• If you find an injured bird, do not try to feed or treat it yourself; ask the municipality or wildlife teams for help.
• Keep quiet at busy watch points, share your binoculars and telescope with others and do not distract volunteers who are counting.

Plans for Two Migration Days

Çamlıca in autumn: Take the M5 metro from Üsküdar to Kısıklı station; from there the hilltop is reached by an uphill walk of about 1.1 kilometres, roughly fifteen minutes. Take up a position towards midday and scan to the northeast; as the thermals strengthen, the birds appear as clusters circling upwards. There are resting and viewing areas within the grove, so a long wait is comfortable. If someone with you is more interested in views than birds, Çamlıca's outlook over the city will keep them happy too. Because most storks pass within a few short weeks in autumn, follow the count announcements if you want to see them.

Sarıyer in spring: After the M2 metro, buses heading between Sarıyer and Rumeli Feneri take you to the tower at Keskin Viraj; check current routes with İETT. There is parking and a paved road next to the tower, and the walking is easy. In the 2006 count the peaks for storks and lesser spotted eagles came in late March, while honey buzzards were most numerous in May; choose your day accordingly. You can end the day at Garipçe or Rumeli Feneri; most storks pass along the line between Garipçe and Poyrazköy on the opposite shore.

If you prefer the northern end of the Asian side, as an alternative to the Beykoz ridges that sources mention as an autumn site, you can take the ferry to Anadolu Kavağı and climb up to Yoros Castle. The castle is not an official count point, but because it looks down on the mouth of the Bosphorus where it opens into the Black Sea, it makes a good stop for watching the sky on migration days.

In winter, turn towards the wetlands. The viewing points of the Nature Park at Lake Büyükçekmece or Kamil Abduş Lake in Tuzla are good places to watch ducks, herons and cormorants on a quiet weekend walk. If you take a ferry home, look out for shearwaters on the waters of the Bosphorus.

Practical Notes

• On the hills, sun and wind together are tiring; bring a hat, sunscreen, water and a windproof jacket. A folding stool helps during long waits.
• Migration comes in waves. If the first hour is quiet, do not give up at once; the picture can change as the air warms or the wind shifts.
• Follow the dates of count events on the municipality's Yeşil İstanbul pages and in announcements by birdwatching groups; joining a volunteer count is the fastest way to learn about migration.
• Opening hours of parks and groves may change; check before you set out.

Sources

• Zeynel Arslangündoğdu, Bir Gökyüzü Şenliği, Magma Dergisi, 2026, https://www.magmadergisi.com/doga/bir-gokyuzu-senligi
• Özkan Üner et al., Spring migration of soaring birds over the Bosphorus, Turkey, in 2006, Sandgrouse 32, 2010, https://osme.org/wp-content/uploads/2019/10/5_Uner_et_al_Sandgrouse32-1_20-33_comp.pdf
• Istanbul Metropolitan Municipality, Yeşil İstanbul, Bosphorus Raptor Migration Count, https://yesil.istanbul/haber_istanbul-bogazi-yirtici-kus-gocu-sayimi
• Kültür.İstanbul, Bird Migration in Istanbul, https://kultur.istanbul/istanbulda-kus-gocu-bir-gokyuzu-senligi/
• Birdingplaces, Çamlıca Hill, https://www.birdingplaces.eu/en/birdingplaces/turkey/camlica-hill
• Birdingplaces, Sarıyer Feneryolu Bosphorus Birding Tower, https://www.birdingplaces.eu/en/birdingplaces/turkey/sariyer-feneryolu-birding-tower
• Trakus, https://www.trakus.org/
• Wikipedia (Turkish), Büyük Çamlıca Tepesi, https://tr.wikipedia.org/wiki/Büyük_Çamlıca_Tepesi
• Wikipedia (Turkish), Küçükçekmece Gölü, https://tr.wikipedia.org/wiki/Küçükçekmece_Gölü
• Wikipedia (Turkish), Büyükçekmece Gölü, https://tr.wikipedia.org/wiki/Büyükçekmece_Gölü
• Wikipedia (Turkish), Kamil Abduş Gölü, https://tr.wikipedia.org/wiki/Kamil_Abduş_Gölü
• Wikipedia (Turkish), Yeşil papağan, https://tr.wikipedia.org/wiki/Yeşil_papağan
• Wikipedia, Yelkouan shearwater, https://en.wikipedia.org/wiki/Yelkouan_shearwater
• Wikipedia, Rose-ringed parakeet, https://en.wikipedia.org/wiki/Rose-ringed_parakeet
• Wikipedia, Yellow-legged gull, https://en.wikipedia.org/wiki/Yellow-legged_gull
• Wikipedia, EBird, https://en.wikipedia.org/wiki/EBird