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Home , Achziv Islands, Bridled tern

Territorial Bridled off cal of after copulation. Then on 3 August (from 09:00 until 09:45), Gert Mediterranean coast of in Ottens observed the two Bridled Terns from the summer 2008 nearest beach at Betzet. At first, one was seen flying around the islet, soon followed by the other. During a survey of the Achziv islands nature re- After a few minutes, both birds flew off quickly, serve, Western , Israel, on 7 July 2008, Eyal chasing each other in ever widening (and up to Miller and Talya Oron (both Israel Nature & Parks several 100 m high) circles away from the islet. Authority) found two adult Bridled Terns Onycho­ After c 2 min they returned, chasing each other prion anaethetus on Nachlieli. This small (c 100 x very closely and at high speed, then one bird 50 m) rocky islet (with a sandy interior) is situated settled out of view and the other flew off over the c 800 m off the Mediterranean shore, just south of sea to forage. This aerial display is known as ‘high the border with . They were easily identi- flight’ and is performed by breeding pairs during fied by the combination of size, dark greyish the start of the breeding season and again after the brown upperparts, narrow white forehead patch egg has hatched (Cramp & Simmons 1983). and greyish neck (excluding the only confusion On both 7 and 13 August, again from Betzet species, Sooty O fuscata, which shows even beach, the birds were observed by GO (from darker blackish upperparts, a blackish neck and 06:15 until 09:45). On 7 August, both birds were more white on the forehead, and which is larger; present and occasionally one would fly around plate 192-193). The birds were involved in court- the islet before settling down out of view. On two ship behaviour amongst several pairs of Yellow- occasions, one was seen to leave the islet in a legged Gull Larus michahellis and c 30 pairs of southerly direction. The first time, it returned after Sterna hirundo. The male offered 15 min with (what seemed to be) a small fish. The the crouched female a small fish while holding his second time, it had not returned by the time GO wings down (with carpal joints held away from left. The events noted for 13 August were some- the body) and stretching his head forward, with what different. After c 2.5 h without any sightings, bill pointed downwards (plate 192). This behav- one bird appeared from the south and settled iour is considered typical at a nesting territory down out of view. Then again, one would fly (Cramp & Simmons 1983). During a subsequent around the island every now and then and settle. visit to the islet on 13 July, EM and TO again ob- On one occasion, the birds performed the ‘high served courtship, as well as territorial behaviour flight’. On 20 August, GO joined EM (and dolphin (by the male) directed towards Common Terns. researcher Mia Elasar) on a survey of Achziv is- Also, behaviour indicative of copulation was lands nature reserve and the surrounding sea area. noted when, after both birds ‘disappeared’ behind Nachlieli was not visited during this survey, in or- a small rock, one was intensively preening, typi- der not to disturb the breeding birds, so the islet

192 Bridled Terns / Brilsterns anaethetus, 193 Bridled Tern / Brilstern Onychoprion anaethetus, adults in courtship, Nachlieli, western Galilee, Israel, adult, Nachlieli, western Galilee, Israel, 7 July 2008 (Eyal Miller) 20 August 2008 (Mia Elasar)

174 [Dutch Birding 31: 174-176, 2009] Territorial Bridled Terns off Mediterranean coast of Israel in summer 2008 was watched from a boat, from c 06:30 to 07:00. adults along the northern coast, from Dor (near One Bridled Tern was present during this time. It , Hof HaCarmel) northward, with most in flew around the boat several times while uttering the summer, especially in August (see below). a few alarm calls and kept returning to the same Elsewhere in the Mediterranean, Bridled Tern is rock (plate 193). One or (probably) both were still extremely rare with one record of an adult at present on 22 August (Oz Horine, via IsraBirdnet). Tsoukalio lagoon, Amvrakikos, Greece, on 6 June However, during a survey on 4 September, EM did 1987 (Handrinos & Akriotis 1997). In Spain, one not encounter any on or around Nachlieli. Finally, at Guadalhorce river mouth, Málaga, on 15 a check of the islet itself on 10 September pro- September 2005 is currently under consideration duced no trace of the terns’ presence there (TO in by the Spanish rarities committee, while another litt). photographed at Ebro delta, Taragona, on 18 June 2008 has not yet been submitted (Ricard Gutiérrez Distribution in litt). A report at Hammamet, Nabeul, Tunisia, Bridled Tern is a species of mainly (sub)tropical on 16 April 2005 has not yet been accepted seas of the Pacific coast of , the (Kieran Fahy in litt). There are currently no records , West , the , the from other parts of the Mediterranean (cf Isenmann , the Persian Gulf, the Philippines and & Moali 2000, Isenmann et al 2005, Thévenot et Indonesia to Australia (del Hoyo et al 1996). In a al 2003, Sherif Baha el Din in litt, Andrea Corso in Western Palearctic (WP) – as well as probably litt, Philippe Dubois in litt, Guy Kirwan in litt, global – context, the most important breeding Peter Meininger in litt). grounds are found in the Persian Gulf, with small- er populations in the Red Sea and at Banc Discussion d’Arguin, Mauritania (Cramp & Simmons 1983, On the regular breeding grounds, the main breed- Thévenot et al 2003). Its movements are not well ing season of Bridled Terns is June-July (Cramp & understood but vagrants have been recorded in Simmons 1983). It is possible that the birds on most western and northern European countries Nachlieli were already present before 7 July. But bordering either the Atlantic Ocean or the North even if this was not the case, then the fact that Sea, mainly in summer (Cramp & Simmons 1983, they remained on Nachlieli for over six weeks Mitchell & Young 1997). means that they were at least behaving territorial- Vagrant Bridled Terns have been noted to be- ly, even though no definite proof of nesting was have somewhat territorially in the WP at least obtained. once before. During July-August 1989, two adults It is possible that most of the records along were present at different coastal localities in Israel’s Mediterranean coast relate to the same in- Belgium and the Netherlands. On a few occa- dividual that happened to attract a mate in 2008. sions, these birds were seen together, and on For example, three records at Ma’agan Michael 5 and 6 July they performed the ‘high flight’ in a (where similar, but smaller, rocky islands are found mixed colony of Common Terns and Arctic Terns off the coast) in consecutive years (19 August- S paradisaea at Terneuzen, Zeeland, the Nether­ 6 September 2003, 21-22 August 2004 and 22-24 lands (Schekkerman & Meininger 1990). June 2005) suggest that one was already prospect- ing suitable nesting sites. Records from 2007 and Status in Israel and Mediterranean 2008 are from more northerly sites, and it is inter- In Israel, Bridled Tern is a regular but scarce non- esting that the only winter record for Israel, at breeding summer visitor to Eilat, at the northern Betzet beach (across Nachlieli), was on 30 January end of the (Shirihai 1996). Up to 20 2008. In all, it seems not unlikely that one or two birds are reported regularly, especially during late birds were already in the breeding area for a while July-August. The largest flock, of 35-40 birds, was but, for lack of definite proof (the birds could not recorded on 1 August 2006 (Noam Weiss, via be recognized individually) this remains conjec- IsraBirdnet), with another notable flock of 36 on ture. 26 July 2003 (Daniel Gelbart, via IsraBirdnet). Since Bridled Terns usually retain their nest sites Apparently, mainly first-summer birds are involved from year to year (Dunlop & Jenkins 1992), the (Shirihai 1996). Most likely these are non-breeders birds might show up again in the area in following from the nearest breeding populations in the Red years. However, by 14 May 2009 the birds had Sea. For the Mediterranean coast of Israel, Shirihai not (yet) returned, nor were there any reports from (1996) does not list any records. During 2003-08, the general area until then (IsraBirdnet & GO pers however, there have been seven records of single obs).

175 Territorial Bridled Terns off Mediterranean coast of Israel in summer 2008

Acknowledgements Colonial Waterbirds 15 (1): 75-82. The help of Sherif Baha el Din, Amir Ben Dov, Handrinos, G & Akriotis T 1997. Birds of Greece. Arnoud van den Berg, Andrea Corso, Philippe London. Dubois, Enno Ebels, Kieran Fahy, Barend van del Hoyo, J, Elliott, A & Sargatal, J (editors) 1996. Handbook of the birds of the world 3. Barcelona. Gemerden, Ricard Gutiérrez, Guy Kirwan, Peter Isenmann, P & Moali, A 2000. Oiseaux d’Algérie / Birds Meininger, Nikos Probonas and Nir Sapir was in- of Algeria. Paris. dispensible for this paper. Without the assistance Isenmann, P, Gaultier, T, El Hili, A, Azafzaf, H, Dlensi, H of Mia Elasar and especially Eyal Miller and Talya & Smart, M 2005. Oiseaux de Tunisie / Birds of Oron (both Israel Nature & Parks Authority), it Tunisia. Paris. would not have been possible to get so close to Mitchell, D & Young, S 1997. Photographic handbook of Nachlieli. the rare birds of Britain and . London. Schekkerman, H & Meininger, P L 1990. Brilsterns in References Nederland en België in juli-augustus 1989. Dutch Cramp, S & Simmons, K E L (editors) 1983. The birds of Birding 12: 233-238. the Western Palearctic 3. Oxford. Shirihai, H 1996. The birds of Israel. London. Dunlop, J N & Jenkins, J 1992. Known-age birds at a Thévenot, M, Vernon, R & Bergier, P 2003. The birds of subtropical breeding colony of the Bridled Tern Sterna Morocco. An annotated checklist. BOU Checklist 20. anaethetus: a comparison with the . Tring.

Gert Ottens, Ganzebloem 14, 3984 CG Odijk, Netherlands ([email protected])

Aberrant Savi’s Warbler trapped at Common Grasshopper, not Savi’s; 2 dark shafts of undertail-coverts instead of white, fitting Common Elburg, the Netherlands, in June 2008 Grasshopper, not Savi’s; 3 p9 seems to be 0-1 mm On 21 June 2008, Bennie van den Brink and shorter than p8 (see plate 196 – detail undertail- Symen Deuzeman were trapping birds at the ring- coverts – in which p9 of the right wing is best vis- ing site ‘Korte Waarden’ near Elburg, Gelderland, ible), fitting Common Grasshopper better than the Netherlands. At c 09:00, BB found a peculiar Savi’s, in which p9 is 1-2 mm longer than p8 (in bird in a mistnet and showed it to SD. Their first fact, Savi’s and River Warbler L fluviatilis are the impression was a Savi’s Warbler Locustella lusci­ only European passerines in which p9 is the long- nioides, which is regularly trapped at this site, but est of all primaries); and 4 the colour of the bird is soon they doubted this identification because the rather olive-tinged, not deep brown as in Savi’s. bird showed some characteristics that also fitted The plumage and structural characters men- Common Grasshopper Warbler L naevia, such as tioned above better fit Common Grasshopper darkish centres of median and lesser coverts and Warbler. On the other hand, the measurements dark shaft-streaks of the undertail-coverts. Some strongly support Savi’s Warbler. Both wing-length relevant measurements were taken and the bird and tail-length are too long for Common Grass­ was photographed. The photographs and measure­ hopper (table 1). The absence of a notch on p9 ments were sent to André van Loon and Kees (CS) and the only very slight emargination on p8 better Roselaar for their opinion. In table 1, some fit Savi’s. Also the broad-pointed tail-feathers and measurements of the bird are presented. It had a the long undertail-coverts with white tips are char- swollen cloaca, indicating a sexually active male. acteristic for Savi’s (Kees Roselaar in litt). Based on the photographs, showing the darkish Based on the ‘mixed characters’, the Elburg centres of the wing-coverts and dark shaft-streaks Locustella could be assumed to be a hybrid Savi’s of the undertail-coverts, and the relatively large x Common Grasshopper Warbler. However, no size, AvL considered the possibility of a hybrid or such hybrids have been described (cf McCarthy at least a Savi’s Warbler showing some influence 2006) and their existence and features can only be of Common Grasshopper Warbler. CSR compared guessed at. It is also possible that Savi’s Warbler is the Elburg Locustella with 12 Savi’s in the collec- more variable than previously known. Even if the tion of the Zoological Museum at Amsterdam, bird was a hybrid, the Common Grasshopper char- Noord-Holland (ZMA). The bird from Elburg differ­ acteristics appear too weak to indicate a first- ed from these as follows (Kees Roselaar in litt): generation (F1) hybrid (both parents representing 1 dark centres of median and lesser coverts, fitting two different species). Possibly, one of the grand-

176 [Dutch Birding 31: 176-179, 2009]