A noteon Oystercatchersfrom the Varangerfjord,NE Norway

R.H.D. Lambeck & E.G.J. Wessel

Lambeck,R.H.D. & Wessel,E.G.J. 1993. A noteon Oystercatchers from the Varangerfjord,NE Norway.Wader Study Group Bull. 66: 74- 79.

Biometricsof 11 breedingOystercatchers, caught during a visitto the northcoast of the Varangerfjord(NE Norway) from 27 Junethrough 1 July 1991, showed very short bills in both sexescompared to moresouthern populations. Incontrast, wing and tarsus tended to be somewhatlonger. Some further data are presented on breeding biology, mainly dealing with replacementclutches. The population ofthe north-Varangerfjord wasroughly estimated at 600 (sub)adults.Based on six recoveries plus an observation ofa colour-ringedbird, it ispostulated thatOystercatchers breeding west of North Cape-Porsangen migrate along the Norwegian coast andchiefly winter in Britain, while East-Finnmark birds fly over Lapland and along the Gulf of Bothniato a yet unknownwintering region on the 'continent'. R.H.D.Lainbeck & E.G.J.Wessel, Netherlands Institute of Ecology- Centrefor Estuarine and CoastalEcology. Vierstraat 28, 4401EA Yerseke,The Netherlands.

Communicationnr. 591 of theCentre for Estuarine and Coastal Ecology, Yerseke.

INTRODUCTION quantitativedata on the occurrence of Oystercatchersinthis area,b) to checkbirds for West-European colour-rings as an With40,000 pairs, as estimatedfor the 1970s (Kalas & easyway of obtaininginformation on migration,and c) to Byrkjeda11981),the Norwegianbreeding population of the (colour-)ringand measure local breeders. The inevitably OystercatcherHaematopus ostralegus isone of the largestin limitedresults, in combinationwith retrieved ringing data, are Europe(see also Piersma 1986). Detailedassessments made available in this note as a stimulus for further work. remaindifficult, however. The coastlineof Norway,so richin fjordsand islands, is extremely long (55,000 km; Kalas & STUDY AREA AND METHODS Byrkjeda11981),and large stretches are poorlyaccessible. Oystercatchersare nowadayscommon even around the TheVarangerfjord issituated in NE Finnmark,at about70 ø N upperends of fjord branches, over 100 kmaway from the and30 ø E (Figures1 and2). Fieldwork,carried out between opencoast. Increasedinland nesting (pers. obs.) further 27 Juneand 1 July1991, was limitedto the northerncoast of complicatesquantification. thefjord. A roadfollows the shorefrom the westernmost end at Varangerbotnup to the island-townVard•) in the east. In Giventhe lengthof thiscountry, which is situated between the general,the coastal hills gently slope into the sea. Between latitudesof 58ø and 71ø N, a geographicalpattern in biome- Varangerbotnand the town of VadsO(Figure 2) hayfieldsand tricsor migratorybehaviour cannot be excluded.Published meadowsare commonalong the shore,further east rocky informationabout measurements of Norwegianbirds is areaswith Empetrum heath predominate. The upper 7 kmof virtuallyabsent (cf. Glutz von Blotzheim etal. 1975;Cramp & thefjord is rathernarrow (1.5 km)with extensive mudflats Simmons1983). However,unpublished data should exist for especiallynear Varangerbotn. Tidal flats also occur near the a populationinthe southwest,near Stavanger. A few villageof Nessebyand some other places. The tidal range at hundredOystercatchers were ringed and measured here in Vads•)is about3 m. A moreextensive description of the area theearly 1980s (G. Toftin I/tt.).Little is knownof the birds is givenby e.g. Lessells& Leslie(1977) and Vaughan (1979). thatbreed at the otherend of the country,in thefar north.As A semi-quantitativedistribution map for Oystercatchers inthe an extensionof an expeditionto NW Russia(Lambeck et al. Varangerand the restof Finnmarkis providedby Frantzen et in prep.),a shortreconnaissance visit was therefore paid to al. (1991). theVarangedjord in NE Norway,an inletof the Barentsz Sea nearthe Russianborder. Aims were a) to collectsome Breedingbirds were caught at the nest,using drop cages and

74 type)was described according to Swennenet al. (1983). Birdswere provided with an individualcombination of one engraved16 mmhigh plastic colour-ring on eachleg, allowingfuture identification bytelescope. Chicks were caughtby handon the shore,and only supplied with a metal ring.

Foreignring recoveries were obtained from EURING. Since thepreliminary account of Holgersen(1962), no overview has beenmade of recoveriesfrom Norwegian-ringed Oyster- catchers.Most of the ringing data from the Stavanger Ringing Centrecould be covered via the (bi-)annual 'Bird-ringing Reports,Stavanger Museum' (published by H. Holgersenup to 1981and O.J. Runde from 1981-1983 in Sterna) and a searchin the presentdatabase containing recoveries from 1986 (O.J.Runde, in litt.). Recoveriesfrom the former Oslo RingingCentre, responsible for 24% of the 3125 Oyster- catchersringed in Norwayup to 1975inclusive (Holgersen 1977),could only be traced up to 1974(cf. Anker- Nilssen et al. 1977). However,an additionalcheck for birdsringed in northernmostNorway could be madein the ForeignRing-files ofthe British, Dutch and German (only from 1987) Ringing Figure1. WestemEurope and the locationof the Varangedjord.Indicated Centres. are placesof ringingor recoveryof three Varangedjord Oystercatchers (&), and placesof ringing(n=3) of fourbirds recovered in the restof Rnnmark/ Tromsregion east of 21øE ( ß ); see alsoFigure 2, RESULTS AND DISCUSSION walk-incages, after replacement of the clutchby plasticeggs Breedingbiology forsafety reasons. Egg sizes were measured with calipers to the nearest0.1 mm. Bodyweight was determined on an Althoughone nest was found over 100 m fromthe water, local electronicbalance with an accuracyof 1 gram. Biometric Oystercatchersusually bred in the upperpart of the shoreline. parameters,viz. lengthsof bill,wing (maximum chord), Clutchsize in 11 nestsvaried between 1 and3 (twowith 1, tarsus+toe(all to the nearest1 mm)and tarsus only (to the twowith 2 andseven with 3 eggs). Includingalso two eggs nearest0.1 mm),were measured according standard pro- fromabandoned nests, the averagesize of the 29 eggswas cedures,and, additionally, the shape of the billtip (feeding 56.2 (ñ SD 2.1) x 39.7 (ñ SD 1.0) mm,with extremes of 59.6 18ø 21ø 24ø 27ø 30ø 33ø E

Figure2. Theq'op ot Norway'with geographical names used in the text. Indicatedare recovery sites of four ringed Oystercatchers between the Varangedjord andthe 21øE meridian ( ß ), andthe placesof ringingor recovery(n=2) of threeVarangedjord birds ( & ).

75 Bill Populationsize

Timewas too short for anydetailed census. Along 7 stretchesof the coastsearched between Ekker6y (11 kmeast 75 of Vads6)and Varangerbotn, comprising 7.4 kin,in total 17 territorialpairs, or 2.3 pairsper kin, were counted. The estimatedshore-length between Varangerbotn and Vard6 (includingVard6 and Vads6 islands and Ekker6y peninsula) is 7O 140 kin. Becausethe North-Varangercoast is hardly indentated,the realshore-length will not be muchlarger. Extrapolationwould then give a populationof 320 pairs.This

65 ß ß ß willbe an over-estimationbecause the easternpart of the ß coast,where densities were apparently lower (see also ß Frantzenetal. 1991),was not sampled. A crudeweighted calculation,assuming an average5 pairs/kmfor the first 10 6O kmfrom Varangerbotn, 2 pairs/kin for the nextstretch of 60 460 480 500 520 540 560 kmup to Ekker6y,and 0.5 pair/kmfor the final 70 kmto Weight Vard6,arrives at 205 territorialpairs. In 1977,9 pairsalong 4.5 kin,or 2 pairs/km,were counted around Nesseby (R6stad Figure3. Therelation between body weight (in g) andbill-length (in mm) for in litt.).Kalas & Byrkjedal(1981) used an estimated1 pair/km 11 breed•gVarangerfjord Oystercatchers. forthe entireNorth-Norway. Three small flocks of intotal 46 non-breederswere seen, all inadult plumage. Assuming this (x39.1) and (57.5 x) 37.0min. This average is nearly categoryto compriseabout one third of the population,as identicalto thatof eggscollected elsewhere in Norway foundon a Dutchisland (Ens 1992), would indicate a (Haftorn1971), and neither is it muchdifferent from figures for (sub-)adultpopulation size of over600 Oystercatchers. otherEuropean populations (see Glutz von Blotzheim etal. Duringour visit we already ascertained the presence of 184 1975). different individuals.

We observedfive pairs with large chicks of overtwo weeks TheBarentsz Sea coast northwest of Vard6is very rugged (threewith 1, onewith 2, andone with 3 chicks),indicating an andexposed. Where the shore could be viewedfrom the 36 onsetof layingbetween 10 and15 May. Birdsnormally arrive kmlong road to Hamningberg,we saweight individuals, herein lateApril (Holgersen 1962). Onemore pair was seen includingat leasttwo territorial pairs, in shelteredbays only. witha chickof aboutthree days, and also an oneegg-clutch Biometrics wasnear hatching. On the other hand, several clutches had beenincubated for only two weeks and a threeegg-clutch foundon 1 Julywas even completely fresh. Considering the Besideseight chicks, 11 breedingadults were caught, advancedseason, the majoritywill have been replacement includingtwo pairs. The partners had clearly different clutches.Fresh storm tide marks and manypairs with only an bill-lengths(64 versus71, and65 versus77 mm,respec- emptynest-hole suggested that many clutches had been tively),the long-bills being the presumed females. One more washedaway in the preceding weeks. A similarphenomenon birdcould be reliablysexed as a femalefrom its brownish wasfound in the RussianBay of Kandalaksha(Lainbeck etal. backfeathers (cf. Cramp & Simmons1983). Thesample is in prep).One nest found was obviously predated, and toosmall for discriminant analysis. Since the average anothertrampled by cattle. Normal clutch size in Finnmark biometricswere nearly identical to that measuredin a larger shouldbe three (Frantzen etal. 1991),but S.A. Nilsen (in litt.) sample(58, of which 14 areof knownsex) of North-Russian claimsfour eggs to bethe rulein the Varanger,clutches with birds(Lainbeck etcl. in prep.),data of thesetwo regions were threeeggs being much less common. combinedto assessthe sex from our Varanger birds.

Table1. Biometrics(mean + SD)of 11 Oystercatchers breeding along the north coast of the Varangerfjord inlate Jun 1991,and of a birdbom here in 1972 andretrapped in the DutchDelta area on 19 and28 March1985.

Sex(sample) Weight(g) Bill(mm) Wing(mm) Tarsus(mm) Tarsus+Toe(mm) Male(n= 6) 491 +_11 64.0+ 1.2 258.8+ 4.9 48.6+ 0.9 92.4_+ 1.5 Female(n= 5) 537 + 8 70.6+ 3.4 261.4+ 5.2 50.0+ 1.3 92.4 + 1.5 Total(n=l 1 ) 512 + 25 67.0 + 4.1 260.0+ 5.2 49.2+ 1.3 92.4+_ 1.5

Varangerbom adult, sex unknown 590 70 257

76 Accordingto discrimantanalysis with weight, length of wing, waderringing expedition to theVaranger in 1974(Lessells & billand tarsus+toe as variables,our sample should consist of Leslie1977). Duringan extensiveNorwegian wader project five females and six males. Their biometricsare summarized aroundNesseby (e.g. Lifjeld 1984), in total 32 oystercatchers in Table 1. (27pulli, three fledged juveniles and two breeding adults) wereringed between 1975 and 1982, without recoveries so Thefemales tended to havea slightlylonger wing and tarsus. far (R•)stadin litt.). Nodifference was found in the lengthof tarsus+toe, however. Thefemales were on average 46 g (9.4%)heavier than the Oneforeign-ringed bird had been reported from the Varan- males,the sex difference inbill-length was also distinct. A ger:an adultcaught on 6 September1929 at the islandof plotof bill-lengthagainst body weight (Figure 3) shows Mellum(Germany) and shot near Kirkenes on 11 May1932. indeedtwo obvious categories in this small sample. Eight Inspectionby usof 166 individualsrevealed one colour- birdshad a chisel-typebill, in two birds the tipwas inter- ringedoystercatcher near Nesseby, which was marked by us mediatebetween chisel-shaped and blunt, and one had a inthe central Dutch Delta on 2 April1987 (since a group- ratherpointed bill. codewas used, this bird was not individually identifiable).

Bill-lengthof the Varangerbirds is strikinglysmall in compari- Whenextending the study area to the Finnmark/Troms region, sonto publisheddata for other populations, where averages westto 21øE (Figure2), thereare fourmore recoveries rangefrom 67.9 - 77.0 mmin malesand 75.3 - 83.8 mmin available.One Oystercatcher was ringed south of Stavanger females(Glutz von Biotzheim etal. 1975;Cramp & Simmons on11 October1950, and shot east of Hammerleston 15 May 1983). Thisdifference is independentofthe billshape (cf. 1953. Theother three were ringed in Britain.One, caught as Swennenetal. 1983). Ourdata provide further evidence for a a juvenileon the Wash (east England) on 14 November1970, north-southgradient in bill-length.This aspect will be wasfound freshly starved to deathon 1 May1975, hence discussedin Lambecket al. (inprep.). shortlyafter arrival. The two others were ringed respectively as anadult on the Wash in lateJanuary, and as "> 1 year"in Theshort bill is nota consequenceof a smallbody size: both West-Englandin mid-September. tarsus-lengthand wing-length are in the upperrange of publishedvalues (cf. Glutz von Biotzheim et al. 1975;Cramp Theextensive ringing programme around the Wash resulted & Simmons1983). Theaverage wing length of e.g.adults in 437 recoveriesfrom Norway up to 1986inclusive, while a winteringin the DutchWadden Sea is 256.2 mm (data C. further46 Oystercatcherswith Norwegian rings were reported Swennen,in Glutzvon Blotzheim et al. 1975)as opposedto fromthe Wash (Branson 1987). Recoverysites cover the 260.0mm in our small Varanger sample. The primaries of the entireNorwegian coastline, and even in the Provinceof latterbirds were, moreover, subjected to an extrahalf a year Troms(between 69 ø and 70 ø N) 21 birdswere reported. The ofwear. OnlyIcelandic Oystercatchers have a roughlysimilar absenceof Britishringed birds in East-Finnmarkistherefore winglength (Glutz von Blotzheim et al. 1975). A iongerwing striking.Conditions for recoveries around the Varanger are maybe an adaptationto facilitatelong-distance migratory noworse than elsewhere in North-Norway.Indeed flights(cf. Winkler & Leisler1992). recoveriesmay be even more likely, considering the many farmsand villages dotted along the coast, and the presence Migration of relativelymany local and foreign bird-watchers.

Thefew ring recoveries of high-northernNorwegian Oyster- Thatthe three recoveries of Varangerbirds are all from catchersare summarized in Figures1 and2. Theonly continentalEurope, points to an alternativeexplanation: a Varanger-ringedbird involved was ringed as a juvenilenear differentmigration mute for the East-Finnmark population. Nessebyon 10 August1972 and retrapped by us in the Thismay be related to the extreme easterly situation of this northernDutch Delta area on 19 Marchand again 28 March areain combination with, compared to thewest-coast, its 1985. Itshigh weight for that time of the year, 590 g onboth atypicaltopography. As a consequence,a coastal mute from dates(Table 1), indicatedpre--migratory fattening. This bird theVarangerfjord to the outer Alta fjord (Figure 2) takes probablywintered in the DutchDelta, since it wasfound c. 500 kmduring which the flightdirection has to be com- freshlydead in the samesector on 17 February1989. pletelychanged three times. The same journey is only c. 250 kmin a straightwestwards flight. However, the other three Thenumber of Oystercatchersringed around the Varanger is mainfjords in EastFinnmark have a north-southaxis, the presumablylow. Theannual figure for entire Norway in the endsof Tanafjord and Laksefjord being more northerly than 1970swas around 200 birds,predominantly chicks (e.g. theVaranger and that of Porsangenbeing at thesame Hoigersen1977). Consideringreports from the Stavanger latitude(Figure 2). Forsuch a short-cutto the NorthAtlantic, RingingCentre, most of these originated from southern birdsshould thus chiefly cross a ruggedsub-arctic mountain Norway.No Oystercatchers were trapped during a British plateau,with peaks approaching 1000 m. Flyingslightly more southwards,e.g. towards the TinmsS) coast, implies the

77 crossingof considerably higher mountain ridges. Meltofte,Mr. S.A. Nielsen and Dr. O.W.R0stad (with thanks to DrJ.T. Lifjeld).Dr. P.J.Herman carried out the discrimi- Therecovery sites of the Norwegian and two of the British nantanalysis. Mr. A.A. Bolsius drew the maps.Dr. J.B. birds in Finnmark still face the North Atlantic. The third was Hulscher,P.L. Meininger and Drs.H. Schekkermanmade recoveredat thewestern shore of Porsangen,with in- usefulcomments on the manuscript. betweenonly an easily crossable peninsula (Figure 2). The scarcedata thus indicate that birds breeding in coastal REFERENCES habitatswest of NorthCape-Porsangen migrate southwards alongthe coast in autumn, predominantly with Britain as Andrew,D.G. 1959. Migrationsof the oystercatcher. Brit. destination. Birds 52:216-220.

Birdsbreeding more to theeast are postulatedto head Anker-Nilssen,T., Adelsten-Jensen,K., Jerstad,K., R•)stad, directlysouthwestwards fora 500-550 kmflight over Lapland O.W.& Thomassen,J. 1977. Ringmerkingavforskjellige to theGulf of Bothnia.The landscape here is muchflatter, fuglearteri 1972 og 1973. Medd.Norsk Viltforskning Ser. 3, withseveral large lakes (including 70 kmlong Lake Inari) and, nr. 2. inthe southernhalf, the valleys of somemajor rivers. When furtherfollowing the Finnishcoast of theGulf, with a likely Bianki,V.V. & Nehls,H.W. 1985. Oystercatcher-Haerna- crossingover the Aland archipelago (Figure 1) towards the topusostralegus L.. In:J.A. Viksne & H.A.Michelson (eds.), SwedishBaltic coast, the presumed flight distance from the Migrationsof Birdsof EasternEurope and NorthernAsia- Varangertowards the DanishWadden Sea is,moreover, Gruiiformes,Charadriiforrnes, pp.87-97 (inRussian). Nauka, about100 km shorterthan the 2,600 km neededfor the route Moscow. overFinnmark and along the Norwegiancoast. The gain is evenlarger when birds would fly directly from South-Sweden Branson,N.J.B.A. (ed.) 1987. WashWader Ringing Group towardsthe western part of the German Wadden Sea. Flying Report1985-86. Cambridge. alongthe Swedish Bothnian coast is notshorter than the Norwayroute, but here also 100 kmcan be wonby a Cramp,S. & Simmons,K.E.L. 1983. Birdsof the Western short-cutvia the large lakes in mid-Swedento theSkagerrak, Palearctic.Vol 2. OxfordUniversity Press, Oxford. andanother 50 kmwhen flying from there directly over Jutland.Such large (low)land-crossings arealso made by Ens,B.J. 1992. Thesocial prisoner.' causes of natural British(Andrew 1959) and Russian birds (Bianki & Nehls variationin reproductivesuccess of theoystercatcher. 1985;Lainbeck et al. in prep.),and further supported by data DissertationRijksuniversiteit Groningen. fromlocal counts in Denmark(Meltofte in prep.). Frantzen,B., DransfeldH. & Hunsdal,O. 1991. Fugleatlasfor Theperiod of autumnmigration is notexactly known. Accord- Finnmarl•Fylkesmannen i Finnmark/Norsk Ornithologiske ingto R•)stad(in I/tt.),Oystercatchers around Nesseby stay Forenening,avd. Finnmark, VadsO. untilat leastmid-September. Given the lack of ringingdata, we cannot drew conclusionson the locationof the main Glutzvon Blotzheim,U.N., Bauer,K.M. & Bazzel,E. 1975. winteringarea of Varangerbirds. It is obviousthat Handbuchder V•gelMitteleuropas. Band 6. Akademische (colour-)ringingefforts in this high-northern breeding area Verlagsgesellschaft,Wiesbaden. shouldbe considerablyincreased to elucidatetheir migration patterns.Additionally, it would be interestingto analyzeby Haftorn,S. 1971. NorgesFugler. Universitets Forlaget, Oslo. biochemicaltechniques whether some genetic differentiation hasdeveloped between the Oystercatchers from West and Holgersen,H. 1962. Ringmerkingav tjeld. StavangerMus. East-Finnmark. ,4rbok1962:175-180.

ACKNOWLEDGEMENTS Holgersen,H. 1977. Ringmerkingsoversikt1975. Sterna16: 81-86. Thevisit to theVaranger area was financially supported by the'Beijerinck-Popping' fund. Mr.O.J. Runde (Stavanger Kalas,J.A. & Byrkjedal,I. 1981. Vadefugleneshekkestatus i Museum)provided us with a ringinglicense, and checked Norgemed Svalbard. Proc. Second Nordic Congr. Ornithol. NorwegianOystercatcher recoveries from 1986. Helpin the 197•. 57-74. Stavanger. searchfor ringingdata was further obtained from R. Was- senaar(Dutch Ringing Centre/EURING), Dr. S.R. Baillie and Lessells,K. & Leslie,R. 1977. Oxfordexpedition to Varanger- W. Peach(BTO), and Dr. K.-M. Exo(Helgoland Ringing fjord,Norway, 1974. Bull.Oxf. Univ. Explor. Club, New Ser. Centre).Additional information was provided by Mrs. M. 3: 27-54. Birkeland(Finmarksbibiioteket), Dr. C.M. Lessells, Dr. H.

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