A Sabine's Gull Xema sabini in Montenegro - first record in the NE Mediterranean and a short review of the species' status in SE Europe
Lastovicji galeb Xema sabini v Crni gori - prvo opazovanje v SV Sredozemlju in kratek pregled statusa vrste v JV Evropi
Urs Kormann1 & Borut Stumberger2
1	Agrarokologie, Georg-August-University, Grisebachstr.
6, DE-37077 Gottingen, Germany,
e-mail: oso@hotmail.ch
2	Cirkulane 41, SI-2282 Cirkulane, Slovenia,
e-mail: stumberger@siol.net
Sabine's Gull Xema sabini breeds exclusively in high arctic zones in the northern hemisphere. While most of the breeding population is concentrated in the Nearctic zone of North America, the Palearctic breeders show a scattered distribution over eastern Siberia, Greenland and irregular breeding pairs on Svalbard. Traditional literature mentions two disjunct subpopulations, which differ both in breeding and wintering grounds (Glutz von Blotzheim 1999). Birds from NW America and E Siberia winter on waters of the Humboldt Current, mainly along the Peruvian coast (15°-20°S). In contrast, birds from NE America, Greenland and Svalbard winter in the area of the Benguela Current west of Namibia and South Africa (25°-35°S). The western Nearctic breeders and presumably the Siberian birds migrate along the American West Coast to their Pacific wintering grounds. In contrast, breeders of NE America, Greenland and presumably the Svalbard population migrate in late summer mainly along the coasts of Western Europe to Africa. This is supported by frequent and yearly observations of the species during that time along Western European coasts (Glutz von Blotzheim 1999). Details of their migration north are less clear. Most of the birds leave their African wintering grounds in March/April, but they seem to take a different, more direct route in spring: observations along the West African coast in April and May suggest that Sabine's Gulls do not follow the coastline up to Western Europe in spring. Instead, they only seem to fly to Mauritania and Morocco, where they change their flight direction towards the north-west to continue directly to their breeding
grounds (Glutz von Blotzheim 1999).
Here we report on the discovery of a putative 2nd summer Sabine's Gull. We observed the bird at noon on 15 May 2010, at the mouth of the right arm of the Bojana River, Ada Island, Montenegro (41°51'53.46"N, 19°20'24.14"E), close to the border with Albania. In the beginning, the bird was foraging on a small, unvegetated sand bank, together with 25 Yellow-legged Gulls Larus michahellis, 25 Black-headed Gulls Chroicocephalus ridibundus, 7 Mediterranean Gulls L. melanocephalus, 35 Little Terns Sternula albifrons, 3 Sandwich Terns Sterna sandvicensis, 6 Gull-billed Terns Gelochelidon nilotica, 2 Grey Plovers Pluvialis squatarola, 2 Kentish Plovers Charadrius alexandrinus, 18 Sanderlings Calidris alba und 6 Turnstones Arenaria interpres. Between 11.30 and 11.55 hrs, we observed the gull at a relatively close distance (40 m), when preening. Shortly after, it was flushed by a passing jogger and flew over the river, where we could study it from ca. 200 m distance until 13.15 hrs when we left the place. During our visit on the next day, we could not relocate the bird. However, it may have been present, but the strong rainfall, very strong wind from the south-east (estimated wind speed: 5-6 Beaufort) and a strong swell of the sea made the search difficult.
The species was identified in the field, where the bird could be identified without a shadow of a doubt as a Sabine's Gull. The first character that drew our attention was the bird's small size: in direct comparison, it was markedly smaller than the Black-headed Gulls
Figure 1: Sabine's Gull Xema sabini (right) in direct comparison with a lst-summer Black-Headed Gull Chroicocephalus ridibundus (left). Note the greyish, slightly bleached neck region. Bojana River mouth, Montenegro, 15 May 2010 (photo: Urs Kormann).
Slika 1: Lastovicji galeb Xema sabini (desno) v neposredni primerjavi s prvopoletnim rečnim galebom Chroicocephalus ridibundus (levo). Glej sivkasti, nekoliko zbledeli predel vratu. Ustje Bojane, Črna gora, 15. 5. 2010 (foto: Urs Kormann).
Figure 2: Sabine's Gull Xema sabini (centre) in direct comparison with Yellow-legged Gulls Larus michahellis. The yellow bill tip is visible. Bojana River mouth, Montenegro, 15 May 2010 (photo: Borut Stumberger).
Slika 2: Lastovicji galeb Xema sabini (desno) v neposredni primerjavi z rumenonogimi galebi Larus michahellis. Vidna je rumena konica kljuna. Ustje Bojane, Crna gora, 15. 5. 2010 (foto: Borut Stumberger).
(Figure 1) and approximated only half the size of the Yellow-legged Gulls (Figure 2). This matches the field ornithological description by Svensson (1999), who describes the species' field ornithological characters as "in between Little and Black-headed Gulls". Secondly, the bird revealed its identity by showing the striking, species-specific three-coloured wing pattern, which we observed on several occasions when the bird was in flight and when it opened its wings to dry them. The bird's mantle and secondary coverts were pale grey, whereas the outer five to six primaries (P5/6-10), the corresponding greater primary coverts and the alulas were black. This black and grey pattern was disrupted by a broad white triangle, which was formed by the secondaries, the remaining inner primaries (P1-4) and several greater primary and secondary coverts. We had another opportunity to study the wing pattern when the bird crossed the river at 11.55 hrs. Last but not least, the head left no doubt about the bird's identity. As can be seen in Figure 1, it showed a dark grey-blackish hood, which became slightly clearer and more faded towards the neck. Furthermore, the bird showed a clearly yellow, but not very intensively coloured bill tip (Figure 2). The combination of the characters mentioned above clearly allowed us to exclude similar gull species such as Kittiwake Rissa tridactyla, Black-headed Gull, Mediterranean Gull and Little Gull Hydrocoloeus minutus, or North American rarities such as Laughing L. atricilla, Franklin's L. pipixcan or Bonaparte's Gull C. philadelphia.
In the field, we first identified the bird as an adult individual, given that the yellow bill tip and
the dark hood corresponded to the description of adult individuals according to our knowledge and the literature we had with us (Svensson 1999). However, we had to readjust this evaluation after comparing our field notes and photographs with more detailed literature. Sabine's Gull is a two-year gull, and according to Olsen & Larsson (2003), up to 5 age classes can be distinguished with field characters: Juvenile, 1st winter, 1st summer, 2nd winter, 2nd summer (in some cases) and adult. Individuals showing a dark hood can either be adult, 1st or 2nd summer. However, most 1st summer birds do not show a fully dark hood yet, but rather a greyish or whitish cap on their heads. Even though birds of that age can differ in the colour of their heads, several indicative characters exist (Olsen & Larsson 2003). First, the primaries' white tips are very small. Second, if the bird already shows a dark head, several white feathers remain. Third, 1st year birds have a dark bill tip, as the tip becomes yellow only in the second year. As our bird showed large white tips on the primaries, a yellowish bill tip (see Figures 1 & 2) and no white feathers on the head, we concluded that the bird was at least in its 2nd year. The distinction between 2nd summer and adult birds is less trivial (Olsen & Larsson 2003). Generally, adult individuals show a very dark black or slate grey hood, and the bill tip is shiny yellow. In contrast, our bird showed a relatively dull dark greyish hood and the yellow area on the bill was relatively small and dull yellowish. Hence, these characters correspond well to the category "putative 2nd summer" in Olsen & Larsson (2003).
The observation documented in this article is interesting in multiple ways: according to older (Vizi & VAsic 1980) and more recent literature (Schneider et al. 2006, Lepage 2007), we conclude that our observation is the first record of the species in Montenegro. To our knowledge, the species has not yet been observed in the North-Eastern Mediterranean (delineation according to Blondel et al. 2010), east of Italy. Neither a request at the national rarities committees nor a crosscheck with avibase (Lepage 2007) yielded evidence for the species in any other country bordering the Mediterranean Sea in the region (Slovenia, Croatia, Montenegro, Albania, Greece and Turkey). Hence, our observation is also the first for the species in the north-eastern Mediterranean and in the southern Balkans. The closest reports in the east come from Bulgaria (1 ad. on 15 May 1988, Hirschfeld & Oreel 1988) and Israel (23 Apr-Jun 2009, A. Cohen pers. comm.). Up to now, all six records of Sabine's gulls in the northern Mediterranean east of France were restricted to Italy (A. Corso pers. comm., Table
Table 1: List of records of Sabine's Gull Xema sabini in eastern-Central Europe, SE Europe and the Eastern Mediterranean Sea
Tabela 1: Seznam opazovanj lastovičjega galeba Xema sabini v vzhodni srednji Evropi, JV Evropi in vzhodnem Sredozemskem morju
Country/ Država	Date/ Datum	Age / Starost (as reported by the rarities committee/ kot sporočeno s strani komisije za redkosti	Comment/ Opomba	National rarities committee representative / Predstavnik nacionalne komisije za redkosti
Austria	24.-29. 8. 2012 1 17. 9. 2012 1 13.-15. 12. 2011 9. 10. 2011 22. 9.-6. 10. 2008 2. 9. 1995 19th century	1st year ad. ad. 1st year ad. 1st year		Leander Khil
Bulgaria	15. 5. 1988	ad.		Bojidar Ivanov
Croatia	Not recorded			Jelena Kralj
Czech Republic	26. 9. 2004 14. 9. 1999 12. 10. 1997 16. 2. 1990 8. 12.1985	ad. 1st year 1st year 2nd year 1st year		Martin Vavrik
Greece	Not recorded			Nikos Probonas
Israel (Mediterranean)	23. 4.-Jun 2009	1st year	Two more observations in the Red Sea	Avner Cohen
Italy (East Coast)	4. 7. 2007 17.-18. 5 2005 4. 7-Aug 2001	1st summer ad. 1st winter		Andrea Corso
Hungary	28. 8-3. 9. 20121 17. 12. 1941	ad. 1st year	Same bird as in Slovakia	Gabor Simay
Montenegro	15. 5. 2010	2 year	This article	
Romania	Present, but data deficient	-		-
Slovakia	25. 8. 2009	ad.	Same bird as in Hungary	Richard Kvetko
Slovenia	Not recorded			Jurij Hanžel
1 Record not yet accepted by the national rarities committee / Opazovanja še ni sprejela nacionalna komisija za redkosti.
1). Four of them were after 2000, among them also a spring observation (1 ad., 17-18 May 2005, Lago di Garlate, Lombardy, N Italy).
According to Ranner & Schütz (2009), only three of the 80 Central European observations between 1960 and 2008 were between April and
May. In contrast, a summary of Table 1 reveals that four of the 20 records in Eastern Europe and Eastern Mediterranean were in spring in April or June. Thus, the fraction of spring observations is significantly higher in South-Eastern Europe than in Central Europe (Fisher's Exact Test, P = 0.0252, calculated
with Langsrud 2004). Interestingly, several authors (Olsen & Larsson 2003, Ranner & Schütz 2009) hypothesize that birds from Svalbard and birds from Siberian populations migrate through the Baltic Sea and continental inland Europe in autumn. According to them, this hypothesis is supported by several observations in the Baltic region late in the year and frequent storm-independent autumn observations of the species in Central Europe. Even though a weak autumn migration through continental Europe is supported by observations so far (Ranner & Schütz 2009), no evidence for such a strategy has been found in spring. In contrast, our findings support potential, although sparse spring migration through the Eastern Mediterranean and Eastern Continental Europe.
Be that as it may, the interpretation of the increasing number of reports on the species in the region is difficult and speculative. Whether the growing number of Sabine's Gulls reported in the Mediterranean (especially the possible clustering of records in spring) reflects a biologically meaningful phenomenon, or was only achieved by an increased observation effort, still needs to be substantiated with more data.
Acknowledgements: We would like to thank Avner Cohen, Andrea Corso, Bojidar Ivanov, Jurij Hanžel, Leander Khil, Jelena Kralj, Richard Kvetko, Nikos Probonas, Manuel Schweizer, Gabor Simay and Martin Vavrik for their help in preparing a complete list of records in the region. Verena Rösch and an anonymous reviewer gave valuable comments on the first draft of the manuscript, and libertybird.com organized an excellent birding trip.
Povzetek
Avtorja pričujočega prispevka poročata o prvem opazovanju lastovičjega galeba Xema sabini v Črni gori. Domnevno drugopoletni osebek je bil opazovan 15. 5. 2010 na obrežju otoka Ada v jugovzhodnem delu države. To opazovanje je hkrati prvi zapis vrste v severovzhodnem Sredozemlju in na južnem Balkanu. Podan je pregled 20 doslej zabeleženih opazovanj v jugovzhodni Evropi in vzhodnem Sredozemlju, sicer pa avtorja ugotavljata, da so spomladanska opazovanja vrste neprimerno pogostejša v južni in jugovzhodni Evropi kot v srednji Evropi. Ti izsledki govorijo o potencialni, čeprav redki selitvi vrste prek vzhodnega Sredozemlja in vzhodnega dela celinske Evrope.
References
Blondel, J., Aronson, J., BoDiou, J.-Y. & Boeue, G. (2010): The Mediterranean Region: Biological Diversity in Space and Time. 2nd edition. - Oxford University Press.
Glutz von Blotzheim, U.N. (1999): Handbuch der Vögel Mitteleuropas. Band 8/3. Charadriformes. 2 Auflage. — Aula-Verlag, Wiesbaden.
Hirscheeld, E. & Oreel, G. (1988): Recent WP reports. — Dutch Birding 10 (3): 147—149.
Langsrud, 0. (2004): Online Fisher's Exact Test. — [http:// www.langsrud.com/fisher.htm], 13/3/2013.
Lepage, D. (2007): Schwalbenmöwe (Xema sabini) (Sabine, 1819). Avibase — The World Bird Database. — [http:// avibase.bsc-eoc.org/species.jsp?lang=DE&avibaseid=861 82656472B476B&sec=map], 19/2/2013.
Olsen, K.M. & Larsson, H. (2004): Gulls of Europe, Asia and North America. Reprinted with corrections. — Christopher Helm Guides, London.
Ranner, A. & Schütz, C. (2009): Erster Nachweis der Schwalbenmöwe (Xema sabini, SABINE 1819) für Oberösterreich und Überlegungen zu ihrem Auftreten in Mitteleuropa. — Vogelkundliche Nachrichten OÖ — Naturschutz aktuell 17 (1/2): 119—128.
Schneider-Jacoby, J., Schwarz, U., Sackl, P., Dhora, D., Saveljic, D. & Stumberger, B. (2006): Rapid assessment of the Ecological value of the Bojana-Buna Delta (Albania/Montenegro). — Euronatur, Radolfzell.
Svensson, L., Grant, P., Mullarney, K. & Zetterström, D. (1999): Der neue Kosmos Vogelführer. — Franckh-Kosmos Verlag, Stuttgart.
Vizi, O. & Vasic, V. (1980): Istorijat ornitoloskih istrazivanja Crne Gore sa bibliografijom. — Glasnik Republickog Zavoda za zastitu prirode — Prirodnjackog muzeja
Titograd 13: 33—55.
Arrived / Prispelo: 30. 10. 2012
Accepted / Sprejeto: 24. 2. 2014