Migration Patterns of Some Regularly Occurring Waders in Bahrain 1990-1992
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Migration patterns of some regularly occurring waders in Bahrain 1990-1992 Erik Hirschreid Hirschfeld,E. 1994. Migrationpatterns of some regularlyoccurring waders in Bahrain1990- 1992. Wader Study GroupBull. 74.36-49. Erik Hirschfeld, P.O. Box 2411, Abu Dhabi, United Arab Emirates. INTRODUCTION annual fluctuations in wader numbers or weather/tides. Counts from different roosts have been combined in a few The PersianGulf harbourslarge numbersof Palearctic cases (for exampleGreenshank Tringa nebularia) where waders both on migrationand in winter. These have the average numberthroughout the year did not differ attracted considerableattention during the recent ten more than ñ 20% between roosts. In those cases where it years (see for exampleEvans & Keijl (1993) for an differedmore (for exampleTerek Sandpiper Tringa overview). When I arrivedin Bahrainin October1989 I cinereusand Redshank T. totanus)counts have been was impressedby the numbersof wadersbut surprised used from one roostonly. Roostingsites used for each over the lack of detailed information on numbers. I could figure are indicatedbelow each graph. onlyfind figuresfrom scatteredand incompletewader countsin the BahrainNatural HistorySociety's files and Note that wader numbers have not been correlated with the onlypublication dealing with this groupof birdsin roostsize in any way, and also that the lumpingof counts Bahrain was a shortpaper by Tucker (1985). After an from differentyears preventsany analysisof annual initialreconnaissance period in late 1989, I set out to fluctuations. Unidentified waders have not been included, performregular, systematic counts of wadersat certain withthe exceptionof the two speciesof Sand Plovers, tide roosts. These counts continued until December 1992, DunlinCalidris alpina and CurlewSandpiper Calidris shortlybefore I leftthe island. This paper summarisesthe ferrugineawhich have been analysed as unidentifiedof abundanceof commonerspecies recorded and is adapted eitherspecies. A brokenline in a graph indicatesan from a forthcomingpublication on bird migrationpatterns extrapolationof values,due to insufficientobserver in Bahrain(Hirschreid in prep.). coverage. Wader ringingwas initiatedin Bahrainin autumn1991 and Histogramshave been usedfor specieswhich occurin has continuedannually since (Hirschreidet aL 1992; lower numbers, and these show actual number of Hirschfeldet aL in press;Mohamed et aL in prep.). individualsper monthat aftsites (i.e. sites otherthan the four describedbelow). METHODS It shouldbe kept in mindthat the state of the tide varies seasonally. The hightide duringthe winter monthsis the The four main roostingareas described below were 'lowest' high tide of the year, sometimes reaching almost a selectedas studysites (Map 1). Only my own counts metre below the highestlate summer hightide. During were included in the statistics in order to avoid anomalies such conditions,waders have more roosting sites to caused by different observers'identification criteria and choosefrom and willthen be scatteredout and perhaps census methods. Each site was normallycovered within missedby a single observertrying to countthem. The one hourof hightide once in each ten-dayperiod comparativelylow winter numbersfor some species are throughoutthe year. Due to annual leave and other thus partly caused by this factor, but also by generally reasons,the sites could howevernot be covered every smaller numbersoverwintering. ten-dayperiod in the same year, so countshave been combinedfor all three differentyears. Informationon speciesstatus in neighbouringcountries have, where not acknowledged,been taken from Bundy et The graphspresent an averageof all (1-3) counts al. (1989), Stagg (1987), Richardson(1990) and Oman (regardlessof the year)for eachten-day period (except Bird List edition3. The firstsentence in each species for Lesser Golden Plover Charadriusmongolus which accountdetails status in Bahrainderived from Nightingale showsall records).Inevitably, some ten-day periods were & Hill (1993) and my own observations. bettercovered than others. Eachten-day period average has then been added, in runningmean format, to the averagesof the period before and the periodafter, and dividedby three to even out aberrantpeaks caused by 36 STUDY SITES Sanadmangroves marsh, Bahrain island (50o36 ' E, 26o09' N): MAN The followingsites (Map 1) were used as studysites for wadersas they regularlyharboured large numbersduring The last, polluted,remnants of mangroveon the island, now belongingto the EnvironmentalProtection high tide: Committee.Situated in the southernpart of the important Tubli Bay, south of Manama. ASRY,Muharraq island (50ø39.5'E, 26013 ' N): ASRY 50 ao Consistsof sandy beaches and one large, sheltered lagoonnear the tip of Muharraqisland. Part of the lagoon •u • ß lies insiderestricted area and was thus minimally disturbed. Rasal Busaytin,Muharraq island (50o36 ' E, 26ø 17' N): RB An area of disused masts and concrete fundaments which attractedcertain species of waders in high numbers. Destroyedby land-fillingin summerof 1992. BAPCOBay, Sitra island (50o38 ' E, 2609' N): BAPCO Sandy beachesand a shelteredbay insidea restricted area belongingto the nationaloil refineryand virtually undisturbed.Species composition is similarto ASRY. o SPECIES ACCOUNTS Oystercatcher Haematopusostralegus Fig. 1 Locationof Bahrain and the study area Jl J.• J3 AI A.• A3 $1 $•Z $3 Ol 02 03 NI N•Z N3 DI D•Z D3 Jl J•Z J3 FI 1• 1;3 MI M2 M3 AI A2 A3 MI M2 M3 Jl J•Z J3 BAPCO Bay, Sitra island. n = 970. Common migrant and winter and summer visitor in small far away from the countingpoint) duringOctober and numbers.The mainstronghold was BAPCO Bay where a November. Oystercatchersstarted to depart in February maximum of 68 were counted on 19 November 1991. and March and all, exceptfor a few summeringbirds, There was a build-upof adultsat the end of July and were gone by May. All birds showed characters(in the Augustand then a secondpeak (presumablyof juveniles, field) of the subspeciesIongipes which is knownto occur but not positivelyaged as they preferedroosting areas too in the Gulf (e.g. Uttleyet aL 1988; Evans& Keij11993). Black-winged Stilt Himantopushimantopus J1 J2 J3 A1 .4,2 A3 S1 S2 S3 O1 02 03 N1 N2 N3 D1 I)2 D3 J1 J2 J3 FI Fl., lB M1 M2 M3 A1 .4,2 A3 M1 M2 M3 J1 J2 J3 Sanadmangroves marsh. n = 813. 37 'Recorded in all months and has bred in small numbers remainingwetlands of Bahrain at this time. The largest since 1990 when colonies were established in the Sanad congregationwas recordedat Nakhl Lawzi where 78 were mangroves,Riffa and the Dumistanarea. The main counted 19 November 1992. concentrationsof migrant/winteringbirds were normally found at Sanad. It was not possibleto separatebreeding Black-wingedStilt has recentlystarted to coloniseArabia birdsfrom migrants,but the figure excludespulli. with breedingtaking place in the UAE, Qatar, Oman and Winteringbirds, presumably arriving from other areas, the Eastern Provinceof Saudi Arabia (Kirwan1992). The occuredduring Decemberto February. The decrease in occurrencepattern in the UAE (or at least Dubaicreek, S. Aprilwas probablydue to local birdsdisappearing into the Aspinallpers. comm.) is slightlydifferent from that of vegetationto nest, and the decrease in July and August Bahrainas mostbirds are seen there from Julyto was probablycaused by post-breedingdispersal by December. breeders. Familygroups were often recordedin the few Little Ringed Plover Charadriusdubius JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN All sites. n -- 68. Regularpassage migrant February to Apriland Julyto (excludinglong-staying individuals within the same month) November. Little Ringed Plover breeds in the UAE, ¸man recorded. The specieswas rarely seen in the traditional and - from time to time - in the Riyadhregion but has not wader roostson the shorebut seemedinstead to prefer yet been recordedbreeding in Bahrain. Small numbers inland habitats like the wet areas around Dumistan. winter in Arabia. The figure showsthe numberof birds Ringed Plover Charadriushiaticula 3O 20 10 (•, : ' : : .... : : : : : : """•'-••"-' ' ' ; ; ; ; I J1 J2 J3 A1 A2 A3 $I 82, $30l 02 03 N1 N2 N3 D1 D2 D3 Jl J2 J3 FI lv2, IV3 M1 M2 M.3 A1 A2 A3 M1 M2 M3 Jl J2 J3 BAPCO Bay, Sitra island. n = 422. A regular migrant, common in autumn but scarcer in winterand spring. Nightingale& Hill (1993) recorded passage also in May. The decrease in November suggeststhat most RingedPlovers passing Bahrain were headingfor winteringareas further south. Springmigrants passedBahrain in comparativelysmall numbers during Marchand Apriland Evans& Keijl(1993) were also surprisedby the low numbersin springin SaudiArabia. The Siberiansubspecies tundrae, which mainly migrates to tropicalAfrica, occursin Bahrain(Hirschreid eta/. in press)which agrees with Uttleyeta/. (1988). 38 Kentish Plover Charadrius alexandrinus 250 150 100 50 0 I ! : : ; ; ; ; ; ; : ; ; ; ; .' : ; : : : .' ; ; : : '- J1 J2 J3 A1 A2 A3 $1 $•. $3 Ol O•. 03 NI N•. N3 DI D•. D3 Jl J•. J3 • • 1•3 ]VII IV[2 N[3 A1 A2 A3 ]VII IV[2 N[3 Jl J2 J3 BAPCO Bay, Sitra islandand ASRY, Muharraq island. n = 8,666. A commonbreeder, which probablyalso occursas a MigrantKentish Plovers are said to pass throughthe migrantand winter visitor. The largestcongregation was Riyadhregion of (inland)Saudi Arabia in Marchto May 470 at BAPCO Bay on 14 November 1990. The numbers and Augustto October. The migrationof Middle Eastern/ fluctuatedwidely and were difficultto interpret,due to this Central Asian KentishPlovers is otherwisevirtually speciesbreeding