On our webpages we repeatedly raised the question of studying migration of birds of prey using satellite telemetry. This method has pluses and minuses compared to traditional ringing, colour marking etc. The review makes an attempt to reveal, at least partly, potential opportunities of the satellite telemetry on the example of studying migrations of the Short-toed Eagle.

Some researchers and birdwatchers oppose the direct installation of satellite transmitters on birds basing on ethic reasons. Their main argument: until the absence of negative impacts is proved the method cannot be used in researches. However, it is not an easy task to receive such proofs. It would require control observations of certain types of transmitters and certain bird species and further processing of results with the use of statistical analysis to minimize as much as possible the effect of random factors. Firstly, the sample of birds should be large enough for such processing, which means installation of a lot of transmitters, secondly we must conduct parallel observations of the control bird group without transmitters attached. But exactly the latter is impossible since nowadays there are no other effective methods designed for long-term tracking of birds in their natural environment. In addition, installation and monitoring of even a single transmitter is still fairly expensive, not to mention their dozens. This fact puts restrictions on the use of this method in favour of its opponents.

However, the value of this method is undoubted, as already mentioned in our reviews on this subject. We would like to demonstrate its effectiveness on the example of tracing migratory movements of the Short-toed Eagles in the researches, periodically held in different countries. In these studies, satellite transmitters were attached both to adults (Meyburg et al. 1998; Darawshi 2009) and under-yearlings of the Short-toed Eagles (Pavon et al. 2010). By now more data are obtained for autumn migration of the Short-toed Eagles from France (Meyburg et al. 1996; Meyburg et al. 1998), Israel (Darawshi 2009) and Spain (Pavon et al. 2010), and less data – for spring migration. The reasons of the latter are that the probability of signal loss increases with time due to wearing or damages of a transmitter’s harness, unanticipated failures in its work or the bird’s death. Apart from identification of the precise route of migration, the velocity of birds, their dependence on weather and other factors, there are also other questions can be answered with satellite tracking. The most intriguing of them: how do juveniles distribute on breeding areas when reach maturity?

Reproductive success for the Short-toed Eagle is now defined quite precisely due to long-term monitoring programs carried out in different countries. For instance, in France over the last eight years, since 2002, there have been recorded successful nest departures of 1,059 juveniles of Short-toed Eagles. At present we can say that the breeding success in Europe is averagely equal to 0.5-0.7 fledglings per a territorial pair (Ivanovsky 2002; Bakaloudis et al. 2005; Joubert 2010; Petretti 2008). Our studies conducted in the north of Ukraine for the last seven years in 10 breeding areas bring similar results. It is also known that the Short-toed Eagles reach the reproduction age when they are 3-5 years old. However, several issues still remain unsolved. In particular: how do juveniles distribute; whether this productivity of population enough for its stable existence or at the expense of this productivity the stability of other less successful populations is also supported; whether at these parameters the further expansion of the species range to the north and east is possible; what happens if breeding success decreases in a particular area; to what extent and for how long its decrease will not lead to the reduction in the population size. The answers are essential to know for providing timely measures for conservation of the species in some regions. Of course, ideally, all possible measures must be taken everywhere and always, but reality dictates its own terms: available resources should be directed in advance to the area where they are most needed, where the situation is about to be critical. Unfortunately, ringing and color marking, as practice shows, cannot give clear answers to these questions. Moreover, the application of these methods is very laborious and requires marking of a large number of birds, and this means increasing disturbance along with low probability of receiving recoveries. In addition, the color marking is also a subject to harsh criticism because of the significant artificial changes in visual perception of marked animals by other birds and humans.
The method of satellite telemetry is assigned to contribute to revealing mysteries of the population dynamics through attachment of transmitters to young birds. On the one hand, the probability of their death is higher than adults, i.e. the effectiveness of this expensive method is certainly reduced, but on the other hand the adaptability of young Short-toed Eagles, just left the nest, is far superior to that of their parents. In the Ukrainian Polesye, for example, after only 1-1.5 months since the moment of leaving the nest, they become completely independent and ready to travel to Africa. If we assume that the installed transmitter, despite all the design tricks, really has a negative impact on a bird life activity, it is more for adults than for juveniles, which are better able to adapt to it.

At present it is conducted the satellite tracking of several young Short-toed Eagles equipped with transmitters in 2008 (Pavon et al. 2010) and 2009 in Province of Alicante in the south-east of Spain, and two birds from the south of Italy (Basilicata). For the latter, continuously updated maps with records of migratory movements are available at the website of the Regional Park of Gallipoli Cognato. According to Italian colleagues the transmitters are designed for 3-4 years of work. Thus, there is a chance to get the first data on the territorial distribution of the Short-toed Eagle. By now we have received confirmation of some pre-existing assumptions: that, at least, Spanish Short-toed Eagles 1 year after birth may not return to Europe but stay summering in Africa, and also concerning the direction of migration of these birds from southern Italy.

Breeding sites of the Short-toed Eagles in Ukraine are located much further from the wintering grounds than of those birds for which satellite telemetry has been already applied. Therefore the results of tracking migrations of our birds would naturally lead to increased interest among researchers. Satellite telemetry will also help to answer the main question: if, year after year, the number of the fledged juvenile Short-toed Eagles in Polesye is declining how much time we will have at our disposal to identify the causes and improve the situation? Take into account it is not just a species at the top of the trophic pyramid and the last link of the food chain. It is a raptor, feeding on raptors: more sensitive indicator of the ecosystem state is hard to find…

Konstantin Pismennyi

References

Ivanovsky V.V. The Short-toed Eagle in North Belarus: present and future // Berkut. – 2002. – Vol. 11, Iss. 2. – P. 158–164. [in Russian]

Bakaloudis D. E., Vlachos C. G., Holloway G. J. Nest spacing and breeding performance in Short-toed Eagle Circaetus gallicus in northeast Greece // British Trust for Ornithology, Bird Study. – 2005. – 52. P. 330–338.

Darawshi S. The ecology of the Short-toed Eagle (Circaetus gallicus) in the Judean Slopes, Israel: Graduate Thesis Research report to R.S.G – 2009. – 17 p.

Joubert B. Bilan des suivis en 2009 // La Plume du Circaète. – 2010. – 8. – P. 2.

Meyburg B.-U., Meyburg C., Pacteau C. Migration automnale d’un Circaète Jean-le-Blanc Circaetus gallicus suivi par satellite // Alauda. – 1996. – 64 (3). P. 339-344.

Meyburg B.-U., Meyburg C., Barbraud J. C. Migration strategies of an adult Short-toed eagle Circaetus gallicus tracked by satellite // Alauda. – 1998. – 66 (1). P. 39-48.

Pavón D., Limiñana R., Urios V., Izquierdo A., Yáñez B., Ferrer M. & de la Vega A. Autumn migration of juvenile Short-toed Eagles Circaetus gallicus from southeastern Spain // Ardea. – 2010. – 98 (1). P. 113–117.

Petretti F. L’Aquila dei serpenti : Prima edizione. – 2008. – 272 p.

Below there are data on the size of breeding populations of Falconiformes and Strigiformes of Ukraine (table). If have a look, they prove that numbers of many raptors go on declining. Compared to the previous one (Red Data Book of Ukraine, 1994) the new edition (Red Data Book of Ukraine, 2009) additionally added two species of Falconiformes and Owls. Numbers of eight species don’t exceed several dozens of pairs. Two species (Red Kite и Pallid Harrier) stopped breeding in Ukraine, another two (Osprey и Lesser Kestrel), are also obviously extinct.
For the last 15 years increase of numbers was noted for 6 species of Falconiformes, while 5 species have decreased, and 5 have a stable population; as for the other, their trend isn’t possible to estimate since they stopped breeding or breed only in few quantity.
Quite a great reduction of numbers has been recorded for the Black Kite, Montagu’s Harrier, Spotted Eagle, Levant Sparrowhawk и Lesser Kestrel. Increased numbers have the Long-legged Buzzard, Imperial Eagle, White-tailed Eagle, Saker и Peregrine Falcons. Stable, with small fluctuations, are populations of the Short-toed Eagle, Booted Eagle, Lesser Spotted Eagle, Golden Eagle, Black Vulture и Griffon Vulture.
As for Owls, growth of numbers was registered for the Eagle Owl, Ural Owl and Great Grey Owl. Trends of other Strigiformes are hard to estimate reliably because these birds are poor studied.

However, if have a look at the data in the Table, our attention immediately be drawn with substantial differences in assessment of numbers of some species. In most cases the reason lies in more intensive researches which allowed to receive new data, giving in the result an impression of “increased” numbers. It refers to the Montagu’s Harrier, Short-toed Eagle, Lesser Spotted Eagle, Black Vulture, Griffon Vulture иEagle Owl.

Table

1. Red Data Book of Ukraine. Animal World. Edited by M.M.Shcherbak. Kyiv: Ukrainska Entsiklopedia, 1994. – 464 p. [in Ukrainian]

2. Red Data Book of Ukraine. Animal World. Edited by I.A.Akimov. Kyiv: publ.house “Globalkinsalting”, 2009. – 600 p. [in Ukrainian]

3. BirdLife International. Birds in Europe: population estimates, trends and conservation status. – Cambridge, UK: BirdLife International, 2004. – 374 pp. (BirdLife Conservation Series No. 12).

Maxim Gavrilyuk

Nowadays, the majority of migrants in Ukraine is considered to pass the country by a wide front, though with the reservation accepted that migrations pass not evenly everywhere but mainly follow “ecological routes”, or, at least, ecologically favorable places (Sevastyanov 1992). Therefore migration of birds of prey can be observed over all the territory of Ukraine. However its intensity differs in different regions and separate places.
There are several reasons of it. Birds with specific trophism (the Osprey, White-tailed Eagle) have to keep usual habitats, and for them migratory “corridors” are expressed more distinctly. Thus, the White-tailed Eagle and Osprey in Ukraine can be much more often met along the Dnieper and other large rivers. However even for these species a part of individuals flies during migration time over all the territory of Ukraine.
The more eurytropic are migrants in terms of their trophism, the more similar to the continuous is their migration front. Thus, the majority of birds of prey pass the country in a broad front. The narrowing of their front of migration is caused by landscape or weather and climate barriers.

To analyze the intensity of migration of birds of prey in the territory of Ukraine we have used the data on the maximum number of the individuals met for one day at one observation point during autumn migration (picture).
Despite small quantity of the data, results confirm that the migration goes by a broad front. Essential influence on the migration intensity is caused everywhere by weather conditions. In peak days of passage the number of migrants can increase in dozens times.

In Western Ukraine there exist two basic flyways − Carpathian and Western (Grishchenko 1994). However M.S.Prushinsky and I.V.Shidlovsky (1996) did not reveal a high intensity of migration: studying migrations of the Buzzard, which is a common migratory species, on five permanent plots they registered autumn flocks of this species up to 60 individuals. In Letychev district of Khmelnytsk region 228 individuals of raptors during peak passage on 24.09.1995 were observed by V.Novak (1996).
In the north and in the centre of Ukraine migration goes by a broad front. In Chernyhiv region birds pass a bit more intensively along theDesna valley, though, in general, the migration is of low activity (Kuzmenko et al. 2008; Yu.Kuzmenko, pers. com.). Downstream the Desna the number of migrating birds, observed at one point, increases − in Vyshgorod district of Kyiv region already is observed to 230 individuals, for example 10.10.2009 (Pismennyi 2009). In Dniepropetrvsk area the number of migrating birds in this or that place more depends on weather conditions, thus going by a wide front (V.Syzhko, pers. com.).
In the east of Ukraine the eastern route of migration is distinguished (Grishchenko 1994), however as for birds of prey, we have no reliable data. In Kharkiv region in the middle course of the river Severski Donets flowing to the south-west, migration of raptors is weak (А. and T.Atemasovs, pers. com.). In Luhansk region, as the buzzards of nominative subspecies are rare on paddage, autumn migration also is of weak intensity. The maximum number of birds of prey for a day can amount to several dozens of individuals (Vetrov 1992; V.Vetrov, pers. com.). In Provalska steppe the maximum registered number was a little more than ten birds (Galushchenko, Moroz 2008). Only in autumn of 2008, after passage of an atmospheric front, during the day it was observed apprx. 1200 Buzzards that is an abnormal case. A little narrowing of a migratory stream occurs along the tributaries of the Seversky Donets, flowing in the southern direction, for example, along the river Aidar (V.Vetrov, pers. com.).
In southern areas of Ukraine, as a whole, migration also goes by a broad front (Pilyuga 2000). Even along the seacoast a high intensity of migration is not everywhere observed. In Skadovsk district (Kherson region) in autumn of 2002 the passage peak was noted 20.10 − apprx. 150 individuals, with the dominance of the Sparrowhawk (Domashevsky 2007).
Against a broad-front migration, with the presence of more or less significant landscape barriers it is probable that migratory streams of birds of prey become narrowed. Such barriers are several Dnieper storage lakes, the mountainous Crimea and shores of seas.
Thus, there is a stream of birds, in the autumn passing around Kyiv storage lake, which width in a lower third is 7 km (Poluda 1992). In its lower reaches, near the village of Lebedivka (Vyshgorod district of Kyiv region) only the Buzzard (not counting other birds) was observed during one day up to 110 individuals. (Domashevsky 1996). However more intensive passage is ten kilometres southward, where on the outskirts of Kyiv the streams of birds migrating along the storage lake and the Desna valley join together (Domashevsky 2002). 25.10.2008 in this territory after the change of weather it was observed a migratory wave with more than 1 thousand birds! (Domashevsky, Demidenko 2009).
The narrowing of the migrants stream is observed by us also in the autumn along the left coast of the Kanivske storage lake though it is not of such a high intensity. Birds bend around it and further fly to the south and south-west. For example, near Kaniv (Cherkasy region) 25.10.2009 we met about 180 ind. of raptors dominated by buzzards.
A similar picture we observed at Kremenchuh storage lake which width in the autumn exceeds 10 km. As it is oriented from the north-west to the south-east, birds in its middle reaches have to fly toward west−northwest direction, forming a stream to fly around a water basin in its upper part. This stream is observed, at least, at the village of Irkliev (Chornobay district) to the village of Kedina Gora (Zolotonosha district). In peak days of passage we recorded there about 300 ind. (3.10.2004) birds of prey.
The territory with a high intensity of migration is Kinburnska Spit (Kherson and Mykolaiv region). 26.09.2006 there were counted almost 600 raptors dominated by the Buzzard (Oleynik et al. 2008).
In Western Ukraine I.Gorban (pers. com.) identifies several points of the narrowing of migratory streams. These are the vicinities of Zhovkva City (Lviv region) where it is observed the constriction of Polissia forest stands transforming in the form of some isthmus in forests of Roztochchia. The maximum number of birds of prey can reach there apprx. 800 ind. Around Shatsky lakes (Volyn region) in some years the number of raptors on passage can reach 300−400 ind. Approximately the same number of birds of prey during a migration peak can be met in Radehiv district (Lviv region).
In Odessa region the increased concentration of migrants is noted along the seacoast and large limans (Dniestrovsky, Tyligulsky, etc.) (Pilyuga 2000).
Rather intensive autumn migration of birds of prey is observed on the Crimean peninsula where three migratory routes (Grishchenko 1994) converge. The birds, flying in the Crimea, possibly, get to the “cauldron” as only few species can dare to fly across the Black sea. Therefore the majority searches for other ways to continue their migration. Enough intensive and various according to species composition is the passage of birds of prey across Tarhankut Peninsula. 16.10.2001 there were observed more than 200 ind. (Domashevsky 2002а) which of course is not maximum for the given place. Along the southern coast of the Crimea birds fly divergently, the narrowing of migrating streams is conditioned there by the Crimean mountains. On the pass of ‘Baidarsky Gate’ S.V.Domashevsky (2002b) 29 and 30.02.2002 observed 1200 ind. of birds of prey each day, dominated by the Buzzard. The migration direction toward the south-east and east seems to be not absolutely logical, moreover the author of the paper specifies that already in 26 km to the east (on the pass of Ai-Petri) all observed birds flew westward. Apparently, the revealed direction of migration is atypical and has appeared because of influence of weather conditions.

Thus, for today we are far from full representation of migrations of birds of prey in Ukraine. Supposedly, not all places of concentration of birds during migration are known. The revealed areas of the narrowing of migratory streams demand further researches and all protection.

If you have any additions to the given paper, we’ll be grateful for the information.

Maxim Gavrilyuk

Vetrov, V.V. 1992. Migration of birds of prey in Lugansk region. In: Seasonal bird migrations in the territory of Ukraine, Kiev: Naukova Dumka, pp.254-258. [in Russian]

Galushchenko, S. V, Moroz, V.A. 2008.Seasonal migrations of birds in Provalskaya Steppe. In: Transactions of Lugansk Nature Reserve, Lugansk. Issue 1, pp. 185-206. [in Russian]

Grishchenko, V.M. 1994. Phenological regularities of autumn migration of birds in the territory of Ukraine. Author’s abstract of PhD thesis, Kyiv, 23 p. [in Ukrainian]

Domashevsky, S.V. 1996. Autumnal migration of birds of prey and some waterfowl in the vicinity of the Kyiv reservoir. In: Proc. of Ukrainian Ornithol. Soc. 1:76-85. [in Russian]

Domashevsky, S.V. 2002. Watching migrations of raptors and waterbirds in lower part of the Desna river. Avifauna of Ukraine 2:52-59. [in Russian]

Domashevsky, S.V. 2002. Observations of the migration of birds of prey in the Crimea. Berkut 11(1):112-116. [in Russian]

Domashevsky, S.V. 2002. About birds of prey migration in the foothills and mountains of the Crimea in autumn 2002. Branta 5: 139-142. [in Russian]

Domashevsky, S.V. 2007. Migration of birds of prey in Skadov District of Kherson Region in October 1992. Branta 10:143-146. [in Russian]

Domashevsky, S.V., Demidenko, Yu.A. 2009. Migration of raptors in the vicinity of Kyiv in autumn 2008. Website of Ukrainian Birds of Prey Research Centre http://raptors.org.ua/en/2009/04/migration-of-raptors-in-the-vicinity-of-kyiv-in-autumn-2008/ [in English]

Kuzmenko, Yu. V., Fedun, O. M., Kornienko, T. M. 2008. Autumn migration of birds of prey in Chernihiv region. 210–216. In: Latest studies on Birds of Prey and Owls. Proceedings of the 3d International Scientific Conference “Birds of Prey of Ukraine”, Kryvyi Rih, 24-25 October 2008. (eds. M.N.Gavrilyuk, G.V. Fesenko). – Kryvyi Rih, pp. 210-216 [in Ukrainian]

Novak, V. 1996. Migrations of raptors in Ukraine//Raptors-Link. Information newsletter on birds of prey and owls of Russia. Vol. 4, Iss. 2. P. 3.

Oleinik, D. S., Redinov, K. A., Formaniuk, O. A. 2008. About migration of birds of prey across the Kinburn Peninsula in autumn 2006. In: Latest studies on Birds of Prey and Owls. Proceedings of the 3d International Scientific Conference “Birds of Prey of Ukraine”, Kryvyi Rih, 24-25 October 2008. (eds. M.N.Gavrilyuk, G.V. Fesenko). – Kryvyi Rih, pp. 281-285 [in Russian]

Pilyuga, V. I. 2000. Some aspects of seasonal migrations of birds of prey in the North-West Black Sea area. In:Birds of the Azov-Black Sea region on the boundary of millenia. Odessa: Astro-Print. Pp. 27−29.

Pismennyi, K. 2009. Communication of 10.10.2009 Autumn migration to birds of prey in Ukraine. Website of Ukrainian Birds of Prey Research Centre [in Russian]

Poluda, A.M. 1992. General characteristics of observable seasonal migrations of birds at Kyiv Storage Lake. In: Seasonal bird migrations in the territory of Ukraine, Kiev: Naukova Dumka, pp.24-53. [in Russian]

Prushinsky, M. С, Shidlovsky, І. V. 1996. Toward the passage of the Common Buzzard in the west of Ukraine. In: Proceedings of 2nd conference of young ornithologists of Ukraine. Chernivtsy, pp.151-154.

Sevastyanov, V. I. 1992. General characteristics of seasonal migrations of birds in Ukraine. In: Seasonal bird migrations in the territory of Ukraine, Kiev: Naukova Dumka, pp.11-23. [in Russian]

First three photo are taken from the paper: Dravecký M, Sellis U, Bergmanis U, Dombrovski V, Lontkowski J, Maciorowski G, Maderič B, Meyburg B-U, Mizera T, Stój M, Treinys R & Wójciak J 2008: Colour ringing of the Spotted Eagles (Aquila pomarina, Aquila clanga and their hybrids) in Europe – a review. Slovak Rapt J 2: 37–52.

The colour marking of birds in Ukraine was not provided yet, but basing on migratory routes, you can meet the raptors marked in other countries, as follows:

Osprey. Colour rings were used in Finland and Norway.
Honey Buzzard. 2008, eighty birds were marked with colour rings in Finland.
Black Kite. Colour rings were used in Hungary; wing tags (98 tags in 2003) in Germany.
Goshawk. Colour rings were used in Hungary.
Marsh Harrier. Colour rings were used in Germany, Hungary, Finland (500 birds were marked in 1995-2008) and the Netherlands.
Hen Harrier. Colour rings were used in the Netherlands.
Montagu’s Harrier. Colour rings were used in the Netherlands, Germany and Hungary; wing tags – in Poland.
Buzzard. Colour rings were used in Hungary and the Netherlands; wing tags – in Germany.
Short-toed Eagle. Birds were marked with colour rings on migration in Israel.
Spotted Eagle and Lesser Spotted Eagle. High-volume colour marking with rings was started quite recently. Not only the birds marked in Belarus can be met in Ukraine as data of telemetry show that even Lesser Spotted Eagles from Germany fly to our area. The Lesser Spotted Eagle is regularly marked with wing tags in Latvia. ‘Windows’ on wings are used in Slovakia.
Imperial Eagle. Colour rings were used in Hungary and Slovakia.
White-tailed Eagle. Chicks on a mass scale are marked with colour rings in Scandinavian and Baltic countries, Poland, Belarus and Russia. According to ringing data a few amount of these birds winter in Ukraine. Польщі, а також в Білорусі, Росії. Невелика частина з цих птахів, як показують дані кільцювання, зимує в Україні.
Peregrine. Colour rings were used in Hungary, Finland and many other countries.
Saker. Colour rings were used in Hungary.
Red-footed Falcon. Colour rings were used in Hungary
Kestrel. Colour rings were used in the Netherlands, Finland, Poland, Germany, Romania and Hungary.

In conclusion we would like to express solidarity with the manifest about not using marking of birds without extreme necessity, because of bioethical considerations. The text of the manifest can be found at our partner’s web-site dedicated to the Short-toed Eagle (http://short-toed-eagle.net/manifesto-against-plastic/).

Maxim Gavrilyuk