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The weather conditions have changed rapidly in the Evros Delta, it is not infrequent. Since last night, the wind blows north northeast, gusting up to 70 km/h. It rained much all night and part of the day. The tops of the hills bordering the valley are covered with snow as the Greek side that Turkish. The temperature is around 3-4 ° C.

The data received every hour from the Bewick’s Swan 854X equipped with a GPS/GSM transmitter indicate that it has not left the roosting place this morning. It is therefore not going to feed on the other side of the valley, in Turkey, as he is doing every day since his arrival in the Delta. Is it something happened? Or will he plays, as expected, the role of “sentinel” that allows us to detect broader phenomena?

4 pm, we left for the Drana lagoon and the marshes of Dimitriades to see what happens. The track is particularly muddy, but it works. After a couple of km, the show is unique: we are facing a sea of swan! Most have their head tucked into their plumage. The others face the storm, trying to resist on their powerful legs. Some are in the water but very close to the shore to avoid being swept away by the waves. Others are dry, on the upper parts of the salt marsh. They are mostly lying to offer the least possible resistance to gusts. It is a unique spectacle, so much swans in such meteorological conditions and in such natural habitats.

We estimate the number of Bewick’s Swans to 8400 which must be added circa 150 Whooper Swans and 50 Mute Swans. It is a new maximum for Bewick’s Swan for the site. But what happens in the Evros Delta? From where are these Bewick’s Swans coming from? From Yamal like 854X or from another places in the tundra of Siberia? Russian colleagues are particularly attentive to the problematic, the Bewick’s Swan is an endemic breeder of Russia. It focuses all the attention of the authorities and scientists in charge of the conservation of nature in the Russian Federation.

By watching and still watching this huge flock, our attention is drawn by a swan preening despite the strong wind. He stretches his neck, smooth, or rather try to smooth his feathers. It is marked with a yellow neckband engraved with a code enabling at distance identification. It is the fourth marked Bewick’s Swan we observe in the Evros Delta. This has certainly been ringed in the Netherlands by colleagues from the Netherlands Institute of Ecology. Despite our best efforts, we didn’t managed to read the code: it was not possible to come closer than 750 m, the light was fading to quick with the night falls, the wind vibrates the telescopes. We’ll be back tomorrow to try to find him !

5100, 5300, maybe even 6000! That’s the number of Bewick’s Swans counted the last days by the ornithologists working for the Evros Delta National Park. The previous record was set around 4500 individuals seen during the previous winter. The number of Bewick’s Swans wintering in Greece is therefore still growing while at the same time the flocks observed in traditional areas in the area of the North Sea are at their lowest.

This is not an easy task to count the swans in the Evros. Indeed, the Delta is shared between Greece and Turkey, making it difficult to carry out coordinated counts; there is also no local team of ornithologists on the Turkish side. Part of the delta is also under military control and therefore can be visited only occasionally and under strictly controlled conditions. In addition, the area of presence of swans is very large, about 350 square kilometers. Moreover a part of it is inaccessible when the river flow is so important that adjacent areas to the main branch are flooded. Additionally Bewick’s Swans are not the only representatives of their genus to winter in the Evros Delta. It is also the case for thousands of Mute Swans (from the steppe – or ancient steppes – of Ukraine and South of Russia) and Whooper Swans (most likely originating from the taiga of Siberia). The counts are therefore often slow and difficult as it is essential to carefully make the distinction between the three species. But the Greek team is particularly experienced, alternating on its territory and throughout the winter, weekly day counts and every two weeks evening counts at the roosts.

Starting today, and for 10 days, the Greek and Belgian teams are joining their force to study in the Evros the behavior of swans, their distribution between the different lagoons, their demographics by determining the proportion of young and brood size. The aim is also to go to see each site where the Bewick 854X equipped with a GPS transmitter on 14/07/2015 in the tundra of Yamal ( Siberia) has been located since his arrival in the Evros Delta on 12/12/2015. That will give the possibility to accurately determine the habitats used by this ” sentinel swan” and their relative importance. Such data are very useful for the conservation of the species giving the possibility, if necessary, to propose appropriate management measures. The GPS localization of the transmitter was set at 1 hour interval from today. This will provide even more accurate data in the coming days. This procedure will be limited in time because it is obviously energy costly and could drain the solar battery.

The sun is shining in the Evros today. Daytime temperature ranges between 10-15 °C. It turns out that almost all Bewick’s Swans left Greece to forage in Turkey. Moreover it has appeared that they didn’t came back on the Greeks roosting places before sunset. We have counted barely 150 individuals arriving at roost before darkness. But the evening was not lost! At 16:48 and then at 17:11 it is in a deafening roar that two compact waves totaling 4500 Ruddy Shelducks have arrived at the same marsh just south of Drana lagoon. This happens in the Evros Delta, and at European level, only in the Evros Delta!

Go up tomorrow at 6:30, before sunrise, to see if the swans were indeed coming to sleep to Greece and to count them, if possible. And perhaps also to observe 854X!

The Bewick’s Swan is really a beautiful bird. It is elegant, graceful. His social behavior is fascinating to observe. The parents care for their young for about a year, they migrate, winter together. Adult relationships are complex. They often communicate with each other with very melodious cries.

They sometimes intimidates each other, opening the wings, raising the neck, chasing each other.

They alternate periods of feeding and rest. By far, in polders of Flanders or the Netherlands, they look like pure white flakes. But in the evening, invariably, they fly off in well-structured flight to join their roosting place located on a large body of water, sometimes situated dozens of kilometers from their feeding site. As much as they are (relatively) tolerant to human activities during the day, they are on their guard after the arrival of darkness seeking to protect themselves from terrestrial predators by sleeping on water.

An idyllic situation? Not really. The number of Bewick’s Swans wintering in the North Sea area (from East to West in Poland, Germany, Denmark, Germany, Netherlands, Belgium and the British Isles) fell by 30% between winter 1994- 1995 and winter 2009-2010. The data of the last comprehensive count conducted a year ago (in January 2015) are not yet available. It seems that the negative trend has continued.

What are the reasons for this decline that can be described as catastrophic? They are largely ignored. But several worrying facts are observed: Bewick’s Swans wintering in the North Sea are have few offsprings (cygnets) in comparison with populations wintering in China and Greece. Over the last 10 winters, the average proportion of cygnets was 10.4%. The recorded maximum was 16.6% during the winter 2012/2013 and the minimum of 4.7% (which is very little!) in winter 2007/2008. These data were collected largely through hundreds of volunteer birdwatchers who count and observe the swans each winter. Furthermore, the British ornithologists of the renowned Wildfowl & Wetland Trust made a chocking statement. Since 2000, they X-rayed 47 Bewick’s Swans during ringing operations conducted in England. Among them, 22.7% contained lead shot. This suggests that despite their status of strictly protected species in the European Union and Russia, Bewick’s Swans are still regularly poached. Finally, and here are the Dutch ornithologists from the Institute of Ecology (Wageningen) who are leading, we observe that Bewick’s Swans regularly change food in recent winters and most of these are linked to human activities: meadows, plowing beets, potatoes, corn stubble. This behavior is it indicative of an unstable situation, unfavorable to swans? Studies are underway. And then there is the arrival, gradual but fast, of thousands of Bewick ‘s Swans in the Evros Delta in Greece. Is it there a cause and effect with the decrease of Bewick’s Swans in the North Sea area? Is it a population shift? Is this a good – or bad news? It is this that try to understand the Belgian, Russian and Greek partners this program.

We must quickly understand what’s going on!

The objective of this program is to understand how and why, within a few years, thousands of Bewick’s Swans have decided to spend the winter in the Evros Delta. Beyond that we hope to participate to understand why the population wintering in the southern North Sea region decline inexorably for 15 years. The first results are … totally unexpected!

The locations transmitted every three hours by the GPS/GSM transmitters carried on by the Bewick’s Swans we ringed in the Yamal Peninsula in August 2015 can be seen by logging on to the geographical application that is to access throughout the link right above this post.

The first two Bewick’s left the Yamal tundra on 11/09/2015. These are the swans 843X and 854X, both are immature males. The following three headed south on 14, 19 and 22 September. No transmission was received so far from the transmitter of the sixth swan, 801X. Is it the consequence of a technical problem? Was the transmitter lost in an area outside GSM network? Was the swan predated by a White-tailed Eagle? Each hypothesis is possible.

The five swans migrate separately, despite having been ringed in the same region within a few days. They all go south, flying over the taiga. But when in sight of Omsk and Novosibirsk regions, the swans 820X, 832X and 865X skew towards the east.

Between 30/09/2015 and 05/10/2015, these three swans stopped separately on Ubinskoye lake located 200 km from the city of Novosibirsk and 1650 km from the mouth of the Yuribey where they have been tagged. After a few hours or a few days stopover, each of the three leaved to the east-southeast, crossed Khakassia, flying over the Altai Mountains. 865X was the first to cross the border between Russia and Mongolia. But he quickly landed on Lake Uvs nur where he halted for two days. He then moved again towards the north, passing the Russian border again reaching a lake at 1200 m altitude near the town of Kak. He stayed there for 12 days. The 28/10/2015, in the early morning, he took the air again and traveled 3150 km in three days to reach the suburbs of Shanghai, China! INCREDIBLE ! After some hesitation, he landed on 01/11/2015 on Poyang Lake, one of the largest wintering site for waterfowl in China with a 3500km² surface and over 500,000 waterbirds counted during the winter. Of these, tens of thousands of Bewick’s Swans. Until now it was thought that these birds were originating from Eastern Siberia, and certainly not from Yamal peninsula situated just at the border with Europe. The Bewick Swan 865X traveled almost 6500 km in five weeks. On 26/11/2015, he was joined by 820X and 832X swans. Incredible triple!

Two other swans also regularly transmit their position. After leaving from Yamal they headed also south overflying the taiga to reach the steppes of northern Kazakhstan. 843X travelled the route in one week. He stops on 18/09/2015 on a small lake and then another where he refueled until 17/10/2015. He flies at short distance only stopping next day on another lake located 270 km to the west. West ! So in the opposite direction of the three Bewicks en route to China! His logger is silent since. The swan 854X followed the same way. Between 5 and 21/10/2015, he stopped on a lake Akpas situated 100 km from Bewick 843X. He left the site to fly towards the southwest to reach the Caspian Sea. After a stop of less than 6 hours in the Volga delta, close to Astrakhan, he reoriented to the northwest, overflying – but not stopping – over the marshes of Kumo Manych where every Red-breasted Goose we had equipped with a transmitter in Siberian tundra during previous summers had a stopover. On 23/10/2015 at 11:00, 854X landed on the liman of Beisug on the east coast of the Sea of ​​Azov.

In less than 48 hours, 854X traveled 2300 km. What will he do next? Continue his journey to the west and join the Evros Delta and the Mediterranean? Or wintering in the Azov Sea? Both sites are only at 1100 km distance.

We are in a triple new situation!

843X will hopefully allow us to discover this new migration route that connects the tundra of Siberia to the Evros Delta via northern Kazakhstan and Azov Sea.

820X, 832X and 865X are in China, in the Yangtze River Basin. Probably no one imagined such a connection with the tundra of Yamal, so close to Europe.

Bewick’s Swans ringed from the same flock, at the same place, at the same time, are going to spend the winter in wetlands situated at 7100 km distance.

The geographical application to view the journey of the Bewick’s Swans equipped with a GPS/GSM transmitter in the peninsula Yamal was realized by Philippe Vandevondele and Yves Tassin from Intergraph Belgium (Hexagon Safety & Infrastructure).

The aerial survey of the estuary of the Yuribey river conducted in Augustus 2015 detects the presence of circa 100 Bewick’s Swans in flightless moult.

This period is crucial for the swans and for all waterfowl. Like every bird species they have to renew annually their plumage. Indeed feathers wears out rapidly by the effect of sunlight (UV) degradation and mechanical process. To replace them regularly is thus a question of survival. But the process is very particular among swans, geese and ducks because they moult simultaneously all the flight feathers and are thus unable to flight for several weeks. This is the flightless moult. It is a period when they may be caught relatively easily for ringing. And it is what we did.

Altogether we caught and marked in Yuribey Delta 23 Bewick’s Swans and 1 Whooper Swan. The last breeds in the taiga and is as far as known rare in the tundra. Among the Bewick’s were 10 adults (5 females + 5 males). These birds were hatched at least in spring 2014. Thirteen yearlings (6 females + 7 males) were also caught and ringes. Yearling is the name given to a swan hatched the previous year.

Every swan was marked with a ring of the Bird Ringing Centre of Russia and a white neck-collar engraved with a 4 digits unique code allowing individual identification at distance.

Six swans were moreover equipped with a satellite transmitters allowing their tracking along the migration route. These devices weigh 22 g and are attached to the neck-collar. They are produced by the Polish company ECOTONE-TELEMETRY and record GPS positions at regular interval – to be determined at request – that are later send via the GSM network. It is thus possible to track nearly in live time the route taken by the tagged bird, to identify its stopover places, to understand its migration strategy, to connect breeding sites to wintering sites and much more.

Here is the id card of each Bewick’s Swan equipped with a satellite tag :

Id	Maturity	Sex	Date	Weight
801X	adult	male	12/08/2015	6.4 kg
820X	adult	male	12/08/2015	6.9 kg
832X	adult	female	12/08/2015	5.9 kg
843X	yearling	male	13/08/2015	6.8 kg
854X	yearling	male	14/08/2015	6.5 kg
865X	yearling	female	14/08/2015	5.5 kg

Thank you to the staff of ECOTONE-TELEMETRY for the continuous development of such efficient loggers.

The tundra of Yamal lies just eastwards of the area where it is known that most Bewick’s Swans winter in the North Sea area.

When surveying the area in July 2014 to study the ecology of breeding Red-breasted Goose and Peregrine Falcon we had noticed numerous Bewick’s Swans moving north presumably to moulting sites. Aerial surveys conducted in the meantime in Baydaratskaya bay (west coast of Yamal peninsula) located flocks of resting swans together with numerous breeding pairs. Yamal peninsula seems thus to be an adequate place to organize an expedition aiming to tag Bewick’s Swans. Noteworthy the government of the Yamal Nenets Autonomous Region is very prone to the development of science and the conservation of Natural Heritage.

No sooner said that done, en route to the Baydaratskaya bay and in particular the Yuribey River estuary! Survey in the tundra was conducted from 07/08/2015 till 25/08/2015 and was organized on two levels: from the grounds, mainly by boat and from the air with a mono-engine seaplane. We were three ornithologists from Russia, Greece and Belgium working together with a naturalist seaplane-pilot.

We were hosted in a field settlement 25 km upstream the estuary of the Yuribey, precisely at 68.54.15 N – 69.27.57 E. The place consists in circa 10 wooden barracks, serves has a logistic base and propose essential goods for sale to the nomadic population of Nenets breeding Reindeers in the peninsula.

Moulting and breeding swans were searched by seaplane flying a grand total of 1925 km. Altogether 1059 Bewick’s were counted including at least 64 nesting pairs. No large flock of moulting Bewick’s was found; the max count was 150 individuals. But swans were not our only target! The highly endangered Lesser-white fronted Goose was also intensively searched for. This species knows a tremendous decline the last decades. This delicate goose species – very similar in plumage to the abundant Greater white-fronted Goose – nests also in the tundra or better the forested-tundra of Siberia. It was formerly abundant also in northern Scandinavia where the current population is estimated around 150 individuals. Interestingly most of the surviving Lesser-white fronted Geese from Scandinavia are wintering in Greece, namely in the Evros Delta. The Evros Delta is really an incredible place!

The survey in Yamal Peninsula has benefited of the support of the Government of the Yamal Nenets Autonomous region and the African Eurasian Waterfowl Agreement (AEWA) – UNEP.

The sudden apparition of Bewick’s Swans in the Evros Delta is puzzling. It is quite a rare event to see a species colonizing a new area so quickly and in such a number. Because we are curious and want to be sure that their future in the area – and beyond – will be preserved, it raises some essential questions:

From where are they coming from, in other words what’s their breeding origin ?

What factor(s) made(s) possible that they have arrived up to the Evros Delta ? Do they were forced to leave from another place ?

What route(s) did they follow to reach Greece ?

What characteristic(s) of the Evros Delta made(s) possible for thousands of Bewick’s Swans to spend safely the winter in Greece ? Are these characteristics adequately integrated in the management plan of the Evros Delta National Park? We need to be sure that the swans will benefit of the ideal condition for many more years.

Let’s begin by the beginning… The migration route.

What do we know already ? We have 2 sources of information: the observation of migrating Bewick’s Swans and the results of ringing. No way concerning the observations, the max number of Bewick’s Swan seen simultaneously in Romania is probably 100, the same for Bulgaria and almost 300 for Ukraine. It seems improbable that thousands of migrating swans have escaped the attention of local ornithologists. But it is not impossible because it is known that Bewick’s Swan are able to fly non-stop up to 2000 km.

Checking the ring recovery database of the Bird Ringing Centre of Russia gives some information regarding a route to Greece.

The data show a strong migration route from the breeding grounds in the tundra of western Siberia to the direction of the well-known wintering grounds situated mainly on the southern North Sea area. The Russian database reports also some movements to the south south-east with one ring recovery in the area of Perm on the west of Ural then another along the Volga between Volgograd and Astrakhan and a third to the Kraï of Stavropol at equidistance between the Caspian and Black Sea. This last location is situated 1400 km east of the Evros Delta.

Further to these finding of dead swans, three visual sightings of marked Bewick’s Swans were made so far during the surveys conducted in the Evros Delta. It concerns swans that were fitted with a coloured neck collar engraved with an unique code allowing individual identification at distance. The first sighting dated 04/02/1997 and concern thus one of the very few Bewick’s observed in the Evros Delta. It was ringed at 3558 km distance in the Pechora delta on 15/08/1992 (see blog 23/11/2015). A second Bewick’s Swan with a neck collar was observed also on Paloukia Lagoon on 06/12/1998. It was ringed by Dutch ornithologists on 27/11/1994 in the Flevoland Polder in the central Netherlands. The distance between both locations is 2004 km. The last neck-collared Swan observed in the Evros Delta was also marked in the Netherlands, in Wieringermeer on 16/12/2006. It was seen in Greece on 18/02/2010.

But very interestingly it was observed earlier in the same winter along the Baltic Sea by the celebrated swan’s specialist of Latvia Dmitrijs Boiko. That particular Bewick’s Swan was thus going to Greece throughout Eastern Europe. Notably that same swan was wintering previously in Welney, Norfolk (United-Kingdom). It was back in the same place the next winter after having visited the Evros Delta, then it was seen the next winter in The Netherlands. It indicates that at least some Bewick’s Swans are able to change regularly of wintering ground.

All these data leads us to one conclusion: we have to investigate further the migration route of the Bewick Swan’s wintering in Greece! Because it seems currently difficult to attempt catching Bewick’s in the Evros Delta without major disturbance let’s go to take the problem by the other way and organize an expedition to the tundra of Russia to tag swans during the summer.

Thanks to Emil Todorov (Societatea Ornitologica Romana) and Boris Nikolov Nikolov (Bulgarian Ornithological Centre, Institute of Biodiversity and Ecosystem Research) for having provided information regarding Bewick’s Swan occurrence in respectively Romania and Bulgaria. The Bird Ringing Centre of Russia is part of the Severtsov Institute of Ecology and Evolution. Reports of neck-collared Bewick’s Swan are managed by the observation platform www.geese.org.

Paloukia lagoon, 04/02/1997 10:45, 25 Bewick’s Swans including a brood of 4 cygnets are resting on the ice. They are found during a survey aiming to search for Slender-biller-Curlews Numenius tenuirostris a much threatened wader species. Extraordinarily, one adult is marked with a blue neck collar inscribed with a 4 digits code. It allows to determine that it comes from the Pechora Delta, on the Siberian breeding grounds. It was marked on 15/08/1992 by a joined team of Russian and Dutch ornithologists.

George Handrinos and Filios Akriotis report in their opus “The Birds of Greece” (Ch. Helm, 1997) eight previous records of the Bewick’s Swan in the country. The first was in 1934 in Kavala, others were in the Evros Delta (3 records), Kerkini (3 records) and Kastoria Lake (1 record). The grand total of individuals is 21 with a maximum flock size of 6.

Since the winter 1996-1997 at least, the Bewick’s Swan is an annual winter visitor in the Evros Delta. The increase is regular, almost 500 ind. are counted during winter 2005-2006, 800 in 2008-2009. The numbers explodes during next winter with 2250 Bewick’s Swans counted simultaneously. During winters 2013-14 and 2014-2015, the flock is estimated at 4500 individuals. A spectacle not to forget! Moreover many thousands of Mute Swans originating from Ukraine and southern Russia and Whooper Swans of unknown origin are wintering in the Evros Delta at the same time. On 28/01/2015 it is not less that 10.800 swans of three species that are counted on the lagoons of the Evros Delta! Probably an European record.

The wintering of Bewick’s Swans in the Evros is closely surveyed and a Russian ornithologist working on the shores of the Arctic Ocean was also coming to the delta to track the swans up to the Mediterranean.

The Evros Delta is a unique place in the Mediterranean with a very diverse biodiversity. It is a National Park worth to paid a visit. A dedicated team of environmentalists, ornithologists and wardens monitor the site and assure its preservation. You are looking for a field trip for the next holidays? See here!

The Bewick’s Swan Cygnus bewickii is a breeding endemic of the tundra of Russia. It means that it is only breeding in this part of the World.

It is easily distinguished from the Mute Swan Cygnus olor by its yellow and black bill and a much smaller size.

The Mute Swan is typical with orange on the bill (photo Didier Vangeluwe).

To tell the difference between a Bewick’s and a Whooper Swan Cygnus cygnus – the third swan species of Eurasia – is much less straightforward! The Whooper has also yellow on the bill but more extensively, it is of greater size and is may be best detected by its long, very long neck with a powerful bill and head. Side to side, the Bewick’s is delicate and slender. The voice could also help to identification. The Mute Swan is … mute but gives a very particular noise with its wings when flying. Both Bewick’s and Whooper are very vocal, frequently calling a “whoop-whoop-whoop” deeper and stronger with a second syllable higher for the Whooper compared to those of the Bewick’s .

The long and triangular bill with a large proportion of yellow is typical of the Whooper Swan (photo Didier Vangeluwe).

Weather conditions prevailing during the winter in the tundra does not allow an herbivorous bird like the Bewick’s Swan to stay all-year round close to its breeding site. It is a long distance migratory species. But not all Bewick’s are wintering in the same area. They are actually 3 distinct zones, one centred on the North Sea, another in South East China and Japan and a third on the southern shores of the Caspian Sea.

Three wintering zones? Really? No! Since 1997, a new wintering zone has been established in Greece, in the Evros Delta. At the cross-road of Europe, Asia and Africa, the Evros Delta is one of the most – if not the most – nature-rich coastal wetland of the Mediterranean. The flock was estimated to 4500 Bewick’s Swans during February 2015. An incredible sight! And a unusual event considering that we are the last years much more used to announce decline and extinction…

But from which breeding grounds are coming these swans? What route do they fly to connect the Arctic to the Mediterranean? What factors make possible that Bewick’s Swans have colonized a new wintering area situated minimum 2000 km from the nearest known “historical” site? Is it needed to take (management or legal) measures to assure their future in Greece?

To answer these questions is particularly important considering that in the meantime the numbers of Bewick’s Swans wintering in the North Sea area have declined by 30% during the last 15 years. A very important and worrying drop!

It is to participate to the understanding of these questions that ornithologists of the Severstov Institute of Ecology and Evolution (Bird Ringing Centre of Russia), the Goose, Swan and Duck Study Group of Northern Eurasia and the Royal Belgian Institute of Natural Sciences (BeBirds – Belgian Ringing Centre) have joined their effort, together with the Evros Delta National Park Management Authority and the Forest Research Institute of Thessaloniki to launch the program “The Odyssey of the Bewick’s Swan – another route to Greece!”

We propose to share our observations and findings with you.