85

DISTRIBUTION, MIGRATIONS AND BIOMETRICS OF KNOTS CALIDRIS CANUTUS CANUTUS ON TAIMYR,

PAVEL S. TOMKOVICW & MIKHAIL Y. SOLOVIEV2

Tomkovich P.S. & M.Y. Soloviev 1996. Distribution, migrations and bio­ metrics of Knots Calidris canutus on Taimyr, Siberia. Ardea 84: 85-98.

Studies carried out in northern Taimyr in 1982-84 and 1990-92 were com­ bined with data from other sources to describe the breeding distribution and densities and the migration of Knots at Taimyr Peninsula, north-central Si­ beria. Morphometries, recent ring recoveries, dates and directions of mi­ gration all support the idea that Knots breeding at Taimyr pass through western Europe to winter most probably in Africa. They also confirm the suggestion that Taimyr cannot harbour the entire flyway population and that an unknown breeding area is still to be discovered in Siberia. On the basis of discriminant analyses of linear dimensions formulae to sex Knots were derived; maximum wing length and bill length were the best predic­ tors. Key words: Calidris canutus - Siberia - Taimyr - population size - migra­ tion - discriminant analysis lZoological Museum of Moscow State University, Bolshaya Nikitskaya Str. 6,103009 Moscow, , [email protected]; 2Depart­ ment of Vertebrate Zoology & General Ecology, Biological Faculty, Mos­ cow State University, 119899 Moscow, Russia.

INTRODUCTION more accurate calculations of the population size. In contrast to the established opinion that Si­ Among long-distant migrant shorebirds, Knots Ca­ berian Knots are longer billed and shorter winged iidris canutus have attracted much scientific atten­ than Nearctic (e.e. isiandiea) Knots (a difference tion (e.g. Piersma & Davidson 1992). In spite of used to separate the two populations in winter and this, there is still much that is not known about during migration; Dick et ai. 1976, 1987; Roselaar Knots (Davidson & Piersma 1992a,b). There are no 1983; Prokosch 1988; Davidson et ai. 1986; Schek­ published data from the Siberian breeding grounds kerman et ai. 1992), recent studies of museum of the nominate subspecies C. e. eanutus, migrating skins revealed similarity in the size of birds from there to its supposed West African winter breeding on Taimyr and those breeding in Green­ quarters (Dick et ai. 1976, 1987; Davidson & land and northeast Canada (Tomkovich 1990, Piersma 1992b). There is great variation in the 1992). Since this finding might have been biased ways that the breeding range of the Knot at Taimyr by the small samples available in museum collec­ is depicted (Kozlova 1962; Cramp & Simmons tions, previous conclusions need to be verified 1983; Dick et ai. 1987; Piersma et ai. 1992). A single with larger samples, especially of live-trapped attempt to estimate the size of the Taimyr breeding birds from Taimyr. A substantial sample of sexed population ofKnot was based on umealistic figures Knots captured and measured on Taimyr in 1990­ of densities and evaluation of the breeding range 1992 allows us to not only make comparisons (Piersma et ai. 1992). Currently available data al­ with birds from non-breeding areas, but also ela­ low us to describe the species breeding range at borate the sexing criteria for Taimyr Knots in the Taimyr more precisely and, consequently, to make hand on the basis of body dimensions. 86 ARDEA 84(1/2), 1996

STUDY AREAS AND FIELD METHODS the forehead, and tarsus length. In 1990-1992 to­ tal length of bill and head (Green 1980) and in Biometric data of 65 adult Knots were collected 1991-1992 length of middle toe without claw in 1990-1992 in the Gusinaya River valley, 7-10 were also measured. The birds were weighed to km east of Knipovich Bay of the at the nearest 0.5 g with a Pesola spring balance in north central Taimyr (76°05'N, 98°32'E). In addi­ 1990-92 and with a beam balance in earlier seas­ tion, measurements of 8 Knots were taken by PST ons. Body masses of egg-laying females were ex­ during expeditions to the following localities of cluded from analysis. north western Taimyr: Dikson area (73°33'N, Collected birds were sexed by gonadal exami­ 800 35'E) in 1982-83, lower Lenivaya River nation at dissection. Individually colour-marked (75°l6'N, 89°30'E) in 1983, and Uboinaya River birds that were engaged in territorial defence and mouth (73°37'N, 82°20'E) in 1984. These sites that sang during courtship were identified as ma­ are all within the Arctic tundra subzone (Chernov les (Whitfield & Brade 1991; pers. obs.). Another 1985), are situated within 20 km from the Kara sexing criterion of captured birds was the breadth Sea shoreline, and are characterized by hilly or of the unfeathered part of the cloaca, perpendicu­ low mountain landscape (heights up to 200 m lar to the body axis, measured with a ruler to the above sea level) with gentle slopes. The water­ nearest 0.5 mm (Soloviev & Tomkovich 1995). shed ridges are dominated by polygonal (medal­ The enlarged bellies of egg-laying females in lion) tundra (Chernov 1985), which is replaced by pairs was used as an additional sexing criterion. If moss tundra and marshes of sedge-grass Carex the sex of a bird was positively identified in one stands at the middle and lower parts of the slopes, of the seasons, the (opposite) sex of their mate(s) respectively. The areas are described in detail el­ followed from this. The sex of 20 birds among 48 sewhere (Tomkovich and Vronsky 1988a,b; Tom­ caught and ringed Knots was not identified with kovich & Vronsky 1994; Tomkovich et al. 1994). certainty, even though all Knots with broods are The weather is cold and humid with regular fogs likely to be males (Whitfield & Brade 1991; pers. brought by prevailing northern and northwestern obs. of individually marked birds). winds. Average July air temperature approxima­ All actively migrating Knots and other flocks ted 4°C. In 1990 and 1991 the timing of snow observed during daily excursions were noted. We melt was normal. In both years low nest predation recorded the number of birds in a flock, their be­ lead to rather high breeding success. The summer haviour and the direction of flight. All birds in of 1992 was extremely late and cold, with quick transit flight were taken into consideration and we depredation ofall nests by numerous Arctic Foxes can not be certain whether birds carried out local Alopex lagopus. movements or were actively migrating. Forty-eight birds were captured on their nests and with broods with the 'luchock'-trap (Prik­ Statistical analyses lonsky 1960). Another 25 Knots were collected For most statistical procedures we used Systat throughout the breeding season (9 June to 5 Au­ 5.0 (Wilkinson 1990), with exception of discrimi­ gust) and measured before skinning. Wing length nant analysis done in SAS (SAS Institute 1987). was measured (to the nearest 0.5 mm) with a stop­ The latter was used to work out the best sexing ped ruler in three positions (Svensson 1984): Ull­ criterion for Knots on the basis of the following flattened wing or minimum chord (wingl), flatte­ measurements: maximum wing (wing3), bill, to­ ned but not straightened wing (wing2), and maxi­ tal head, tarsus and middle toe lengths. Complete mum length - flattened and straightened wing series of measurements were only available for (wing3). The other measurements were taken specimens collected in 1991-92, representing with calipers to the nearest 0.1 mm, and consisted about two-thirds of the total sample. This pre­ of bill length from bill tip to the feather-line on empted the application of stepwise discriminant Tomkovich & Soloviev: KNOTS ON TAIMYR, SIBERIA 87

80' 90' 100" 110" 120' 130"

Fig.1. Breeding distribution of Knots on Taimyr and southerly records of Knots in spring; a (black dots) proved case of breeding (nest and/or chicks found), b (circles) possible breeding (distraction dislays recorded), and c (black triangles) spring records at southern Taimyr and in Central Siberia. analysis on the basis of the complete data set. In Azen 1979). Average probabilities of erroneous an analysis for 31 Knots with all five measure­ classification were estimated following the formu­ ments taken, the middle toe length was the first to las of Deev (1977). The probability of misclassifi­ fall out (see below). Then the stepwise analysis cation was also estimated after applying the discri­ was used for a subsample of 46 birds for which minant functions to a training sample. measurements of wing, bill, total head and tarsus length were available. We excluded measurements in stepwise analyses after the F -statistic exceeded RESULTS the 0.05 probability level (Ahrens & Lauter 1981). To avoid the loss ofinformation resulting from the Spatial breeding distribution exclusion of birds with less than four measure­ The data on fauna and status of birds are avai­ ments, we repeated the discriminant analysis for 1able for more than 110 sites in the Taimyr Penin­ the best subsets of measurements. The possibility sula. Twenty breeding localities of Knots are of unequal covariance matrices was considered known now in the region (Fig. 1, Table 1). Nest­ (Davis 1986) and equal prior probabilities to be­ finds or the presence of unfledged chicks, or long to either sex were used to derive the discrimi­ fledglings confirm breeding for 18 of these sites. nant functions (Ahrens & Lauter 1981, Afifi & At sites #3 and #20 distraction displays, presuma- 88 ARDEA 84(1/2), 1996

Table 1. Breeding records of the Knot at Taimyr. N- nests, Ch - unfledged chicks, D- distraction displays, B­ birds with brood patches, Y- badly flying juveniles. Sources are personal communications, unless otherwise stated. Site numbers (#) refer to Fig. 1.

# Date Observ. Locality Source

1 4 Ju11992 N E of Dikson (mainland) A.E. Volkov, J. de Korte 2 5 Aug 1983 N&Ch N of Dikson (mainland) Tomkovich & Vronsky 1988b, A.E. Volkov 3 22 Jul1984 D near Uboinaya R. Mouth Tomkovich & Vronsky 1994 4 25 Jun-13 Jul1983 N lower Lenivaya R. Tomkovich & Vronsky 1988a 5 7-18 July 1990 N&Ch E of Sterlegova Cape Hatker 1995 26-27 June 1991 N 6 24-26 June 1994 N Tolevaya River P.-E. JOnsson 7 24-26 June 1994 N Opalovaya River E. Lappo & E. Syroechkovsky jr 8 22 Jun-29 Jul1901 N&Ch near wintering place Pleske 1928 of the 'Sarja' ship 9 11 July 1901 N Taimyr Island Birula 1907 10 1August 1901 Y Waltera Bay Birula 1907 11 18 July 1989 N Shturmanov Peninsula Hatker 1995 12 29 July 1901 Ch Chemyshova Bay Biru1a 1907 13 since 2 July 1949 N Baklund Peninsula Sdobnikov 1959 14 Jun-Aug 1990-1992 N&Ch Gusinaya River basin Tomkovich et at. 1994 15 early July 1990 N middle Malinovskogo R. I.I. Chupin 16 27-28 June 1994 N Tessema River P.-E. JOnsson 17 30 Jun-2Aug 1994 N Topographov River E. Lappo & E. Syroechkovsky jr 18 24 Jun-5 Jul1978 N Pronchishchevoi Bay Leonovich & Veprintsev 1980 19 22 Jun 1991 N Pronchishcheva Lake Underhill et at. 1993 20 21 Jul1928 D&B Yamu-Tarida River Tugarinov & Tolmachev 1934

bly given near broods, were observed. Apart from June on the Anzhelika River (77°23 'N, 102°51 'E) site #20, all localities are along the northern and and the Pakhra River (77°30'N, 102°50'E), on eastern shores of the Taimyr Peninsula within the 30 June - 2 July on the Neizvestnaya River Arctic tundra subzone at a maximum distance (76°IO'N, 111°27'E), but no hard evidence of from the sea of 30 km (site #19). The only proba­ breeding was found. They were also recorded on ble far-inland record of breeding Knots at site #20 30 June 1991 at Kolosovykh Island (74°57'N, was made on a watershed near the Yamu-Tarida 83°87'E), near the Pushkin Hill (73°l5'N, River at the southern side of Taimyr Lake. Two 86°15'E), and in pairs near the middle stream of males, collected there in different places on 21 the Lenivaya River (75°l5'N, 89°39'E; Hotker July 1928, showed distracton behaviour (Tugari­ 1995). The two latter records are far inland, but no nov & Tolmachev 1934) and had large incubation indication of breeding was obtained. patches (collection ofZoo!' Inst. of Russian Acad. Knots were not found in polar deserts, Sci., St. Petersburg). whether at Chelyuskin Cape, the northernmost Knots were found displaying at several other promontory of Taimyr, or at and coastal places during the Swedish-Russian expe­ Nordenskiold Archipelago (Syroechkovski & dition 'Tundra Ecology '94' on 24-26 June on the Lappo 1994). Thus the Pakhra River is possibly Zarya Peninsula (75°58 'N, 93°48 'E), on 27-28 the northernmost site of the species breeding Tomkovich & Soloviev: KNOTS ON TAIMYR, SIBERIA 89

Table 2. Breeding densities (n/km2) of Knots at Taimyr. Sources are personal communications, unless otherwise stated. Site numbers (#) refer to Fig. I. site (#) Density Source

1 0.5 males Tomkovich & Vronsky 1988b 3 0.1 pairs, or less Tomkovich & Vronsky 1994 4 1-4 males Tomkovich & Vronsky 1988a, pers. obs. 5 1.3 pairs Hotker 1995 12 1-2 pairs, locally Tomkovich et at., 1994 up to 5 nests 14 rather high Leonovich & Veprintsev 1980, v.v. Leonovich 15 0.07-0.12 nests Underhill et at. 1993 15 0.06 ?males Spiekman & Groen 1993

Table 3. Long-distance controls and recoveries of rings from Knots marked in the Knipovich Bay area, northern Taimyr (76°05'N, 98°32'E); +:= shot, C:= controlled, A:= caught by dog, exhausted, pull.:= pullus, M:= male, F:= fe­ male, ad.:= adult. ringno. Ringing details Recovery details Sex, age Date Date Recovery locality Fate

------PB-154209 pull. 13-7-90 25- 8-90 Bottsand, Germany 54°25'N 100 16'E C P-904839-42 pull. 13-7-91 16- 6-95 TefenbUll-Spieker, Germany 54°25'N; 8°48'E C P-904904 pull. 19-7-91 12-10-91 Esnandes, France 46°15'N 1°05'E + P-904820 F, ad. 5-7-91 1- 5-92 Baie de l'Aiguillon, France 46° 16'N 1°HE C P-904913 M,ad. 20-7-9 12- 9-93 Haute-Marne, France 50 0 58'N 1°56'E + P-215596 M,ad. 15-7-90 26- 9-91 Kongea river, Denmark 55°23'N 8°39'E A range. Remarkably, Knots were also absent in the study site (#14) were quite stable from year to Pyasina River delta within the limits of the spe­ year (Tomkovich & Soloviev 1994). cies breeding range during 1989-1993. Breeding densities of Knots were not uniform Ringing recoveries within the range (Table 2). High densities, excee­ Until recently, no recoveries of Knots of the ding one pair per km2, were encountered in the nominate race were known from the breeding central parts, with low densities west to the Pya­ grounds, which promoted the search for indirect sina River and near Pronchishcheva Lake (site indications of links between the West African #19 in Fig. 1). A preliminary density estimation of wintering areas and Siberia (Dick et at. 1976, 1-10 pairsfkm2 near Sterlegova Cape by P. Prok­ 1987; Roselaar 1983; Underhill et at. 1989; Tom­ osch (Piersma et at. 1992) was later refined from kovich 1990; Piersma et at. 1992). In 1990-1991, the same data as 1.3 pairsfkm2 (Hotker 1995). The 48 adult Knots and 118 unfledged chicks were report of four broods per km2 in the Dikson area ringed in the Knipovich Bay area. This resulted in in 1983 (site #2) (Rogacheva 1988) is incorrect, 6 long-distant recoveries from Europe (Table 3). because these four broods were found on a total One more bird, marked as downy young at Ster­ area of at least 18 km2 (Tomkovich & Vronsky legov Cape (site #5 in Fig. 1) on 28 July 1994, 1988b). Densities of breeding Knots at our own was found shot on 20 October 1994 in Le Crotoy, 90 ARDEA 84(1/2), 1996

Table 4. Direction of movements of Knot flocks (in (Yenisey Bay) Knots migrated predominantly in a %) during spring (June) and autumn (July-August) in NNE-direction in flocks up to 40 birds in 1993 the Knipovich Bay area in 1990-1992. (Frodin et al. 1994). For the Knipovich Bay area (site #14) 60.8% of the Knots passed in northerly Direction June July-August to easterly directions (Table 4), the birds see­ n = 163 n = 393 mingly following the coastline. That 36% migra­ ted in westerly directions may be due to heavy N 10.4 7.6 NE 16.0 11.5 snow cover upon arrival in 1992, which might E 34.4 9.7 have lead to reverse migrations. SE 2.5 0 The available published data shows that the S 0.6 4.3 date of first arrival of Knots within the breeding SW 0 17.0 range at northern Taimyr (Table 5) varied with W 15.2 47.3 climatic conditions. In years when the tundra be­ NW 20.9 2.5 came snow-free on average or early dates, Knots first appeared 7-10 June. In years with late springs this only occurred on 13-14 (-21) June. Note that France. Although all recoveries are from migra­ spring migration is not very outspoken. The avai­ tion periods, the data provide the first evidence lable data suggest that in normal and early years that Taimyr Knots indeed migrate along west Eu­ there is a rapid passage, with most birds passing ropean seaboard during both southward and during a period of 4-9 days in the first half of northward migration. June. In the late seasons of 1992 and 1993 pas­ sage lasted for 12 days up to the last decade of Spring arrival and passage June (Table 5). Knots arrive from the west. On 10 June 1984, The southern and central parts of Taimyr when migration near the Uboinaya River mouth tundra were more often visited by observers than was the most pronounced (site #3 in Fig. 1), seven the northern coast. In spite of this, there are very flocks, consisting of 6-54 Knots each (154 birds few spring records of Knots south of the breeding in total), passed eastward along the coastline, and range shown (Fig. 1, Table 6). The occurrence in few flocks on other days behaved similarly (Tom­ southern Taimyr in 1932, 1992 and 1994 all oc­ kovich & Vronsky 1994). At the curred during cold springs, but this explanation

Table 5. Spring migration (dates of arrival) of Knots in northern Taimyr. Site numbers (#) refer to Fig. 1. site (#) spring first record last arrival Source

Sibiryakov lsI. late 10 Jun 1993 21 Jun 1993 Frodin et ai. 1994 2 normal 9 Jun 1982 no data Tomkovich & Vronsky 1988b 3 early 8 Jun 1984 16 Jun 1984 Tomkovich & Vronsky 1994 Pyasina R. mouth normal 7 Jun 1990 11 Jun 1990 Htitker in Piersma et ai. 1992 no data 20 Jun 1990 Htitker 1995 normal 7 Jun 1993 no data Van Dijk & Venema 4 late 14 Jun 1983 no data Tomkovich & Vronsky 1988a 6 ? 9 Jun 1901 no data Birula 1907 11 late 21 Jun 1949 no data Sdobnikov 1959 12 normal 7 Jun 1990 10 Jun 1990 Tomkovich et ai. 1994 12 late 13 Jun 1992 24 Jun 1992 Tomkovich et ai. 1994 Tomkovich & Soloviev: KNOTS ON TAIMYR, SIBERIA 91 can hardly be applied to every spring record in westward pattern. In total, 64% of Knots passed southern Taimyr. In 1960 Knots were found on to the west and southwest in 1990-1992, even Maloye Khantayskoye Lake, north boreal area, though the number of birds flying in opposite di­ when spring proceeded normally (Leonovich & rections is also considerable. Uspensky 1965), and in the early spring of 1988 a Knots congregate in small groups (Tomkovich flock was seen in the central part of the Putorana et ai. 1994) or accompany golden plovers Piuvia­ Mountains. These southerly records, together iis spp. already from late June onwards. Flocking with records from Middle Siberia (Fig. 1, Table 6) became obvious from early July (Tomkovich & suggest an alternative migration route to as yet Vronsky 1988b, 1994; Tomkovich et ai. 1994). A unknown breeding grounds (Piersma et ai. 1992; bimodal pattern was found in 1990 and 1991, fe­ Tomkovich 1992). Observations of Knots in males leaving the area before the males involved southern and northern Taimyr are made at similar in brood rearing (Tomkovich et ai. 1994; pers. dates (Table 5), demonstrating that Knots pass obs.). The latest record of a female at Taimyr was through the different regions at the same time. made on 24 July 1991 at a late nest in which chicks hatched on 26 and 27 July. The latest adult Departure Knots in the Knipovich Bay area in 1990-1992 The few published observations on flight di­ were observed on 9-11 August. Russian museum rections of post-breeding Knots indicate west­ collections do not contain adult Knots collected at ward and southwestward passage (Birola 1907; later dates. Tomkovich & Vronsky 1988a; but see Syroech­ In 1992, a year with late breeding and heavy kovski & Lappo 1994). Observations in the Knip­ egg-predation, the pattern of flock formation and ovich Bay area (Table 4) confirm the primarily departure of Knots differed. Flocking started at

Table 6. Spring records of Knots (number of birds in flocks) in South Taimyr and Central Siberia. Sources are personal communications, unless otherwise stated. R= river or river mouth, L.= lake, M.= mountains.

Site Date Numbers Source

Southern Taimyr

Boganida R 9 June 1843 >2 Middendorff 1853 Tonskoye L. 14-22 June 1992 1-20 Karpov et at. in press Bolsh. Balakhnya R. 17,29 June 1932 8-20 Scalon 1935 BludnayaR. 19-21 June 1994 1-3 M.Y. Soloviev Khantayskoye L. 5,7 June 1960 1-50 Rogacheva 1988,1992 GulyamiR, PutoranaM. 9 June 1988 5 Romanov in press Essey L. 16 June 1905 ? ColI. Zool.Inst., St.-Petersburg

Middle Siberia

YeniseyR. 14 June 1900 4 ColI. Nat.Hist.Mus., Tring VoroL., N. Tunguska R 6, 10 June 1973 1-3 Vronsky 1977 Vilyuchan, Vilyui R 6-7 June 1965 12-15 Andreev 1987 Udachnyi, Vilyui R. 10 June 1974 ? Piersma et at. 1992 Zhigansk, Lena R. 11 June 1974 ? Piersma et at. 1992 92 ARDEA 84(112), 1996

Table 7. Morphometric data (mm) and body mass (g) of adult Knots measured alive or freshly collected at Knip­ ovich Bay area. Shown are samples size (n), range, mean and S.D. for males and females. Wing 1= unflattened wing or minimum chord, Wing 2= flattened but not straightened wing, Wing3= maximum length - flattened and straigh­ tened wing, Bill= length from bill tip to the feather-line on the forehead, Head= total length of bill and head, Mid­ dle toe= length of middle toe without claw.

Measurement Males Females

n range mean SD n range mean SD

Wing1 38 150.0-169.5 160.7 4.1 15 160.0-170.0 165.9 3.0 Wing2 38 151.0-170.0 161.6 4.1 15 161.0-171.0 166.9 3.1 Wing3 38 158.5-177.0 169.0 4.2 15 166.0-179.5 173.2 3.8 Bill 38 30.3-36.5 33.7 1.6 15 32.2-38.1 35.8 1.6 Head 31 58.3-66.0 62.9 1.8 15 61.2-67.6 65.4 2.1 Tarsus 38 29.5-34.9 32.4 1.2 15 30.4-35.2 33.0 1.4 Middle toe 21 23.3-25.7 24.8 0.7 10 24.0-26.5 25.1 0.8 Body mass 37 107.7-160.0 129.0 10.7 11 129.0-157.0 140.1 8.0

the usual time, but a single large wave of migra­ 5 August in 1990 and 1991 near Knipovich Bay, tion occurred in the third week of July. Knots had on 9 August 1984 near the Uboinaya River mouth almost totally vacated the tundra by early August (Tomkovich & Vronsky 1994) and, in the late sea­ (Tomkovich et al. 1994). Accelerated flocking and son of 1983, on 12 August near Dikson (Tomko­ early disappearance of Knots from Taimyr in this vich & Vronsky 1988b). Sdobnikov (1959) men­ and other late years is also reported elsewhere tioned a change of bright rusty underpart-colour (Tomkovich & Vronsky 1988a; Spiekman & to whitish in flocks from 5 August 1949, what Groen 1993; Hotker 1995). probably indicating the appearance of young The first independent young were recorded on birds. He recorded the last immature on 1 Sep­ tember in that year. Kozlova (1962) reported the presence of fledged Knots in the collection of 18 o females Zoological Institute in St. Petersburg shot in • males 16 o Pronchishchevoi Bay on 9 August 1936, west of o 14 0 Taimyr on on 3 and 6 September, and E 0 on Shokal'skogo Island on 3 September (year .s 12 ..c unknown). These are the latest records. '6 10 0 o 0 ca The earlier information on the departure of Q> • .., .• 0 ..c 8 db 0 Knots from Taimyr is scanty and contradictory. It ca • • • 0 •• • ·0 ,., ca 6 • •• • includes a number of presumably erroneous state­ u0 • ...... ments by Sdobnikov (1959) and Birula (1907). 4 • • 2 Morphometries and sexual size dimorphism O~-:;,;;-----;!;:;---;:;,;:-----;,::-----,~--::'::-----"L-J The morphometric data show a clear sexual o 10 20 30 40 50 60 70 days from 1 June size dimorphism (Table 7). Analyses of normal probability plots demonstrated that all characters Fig. 2. The cloaca breadth of male (black dots) and fe­ are sufficiently normally distributed to use para­ male (circles) Knots in the breeding season. metric statistical methods. Mean values of most Tomkovich & Soloviev: KNOTS ON TAIMYR, SIBERIA 93

body dimensions differ significantly between ma­ ted to be equal for either combination and much les and females (Student's t-tests, P< 0.002), with smaller than any other combination of measure­ the exception of tarsus length (P= 0.176) and mid­ ments. Since wing3 and bill length are the tradi­ dle toe length (P= 0.335). Note that the width of tional measurements, we choose the following the cloaca did not exceed 9.5 mm for males, whe­ discriminant function: Z= wing * 0.175 + bill * reas in females before 30 June it always exceeded 0.716. A male will have a Z-score that is smaller 10 mm (Fig. 2). than Zo= 54.747. Otherwise the bird should be fe­ We calculated head length by subtracting bill male. The probability that a bird with a particular length from total head length. Mean values for Z-score is female can be found with the formula males and females are 29.1 mm (SD= 0.8, n= 31) of Afifi & Azen (1979): P= 1/{ 1 + EXP[-Z + Zo]} and 29.6 mm (SD= 0.9, n= 15), respectively. (the probability for a bird to be male is 1 - P). This These values are not significantly different (P= procedure allowed us to sex 5 out of 20 unsexed 0.075), and calculated head length should, there­ Knots with a probability larger than 0.9. All of fore, not be used for sexual identification or for them turned out to be males which were captured geographical comparisons. Total head length has near broods. the distinct advantage over bill length that it is not affected by different degrees of wear of feathers at the bill-base; head length lacks this advantage. DISCUSSION The strong correlation between bill and total head length (r> 0.88, P< 0.01 both for males and fema­ Breeding population estimate les) suggests that it is mainly the bill that determi­ The presently documented breeding distribu­ nes total head length. tion agrees rather well with the opinion of P. Another group of strongly intercorrelated Prokosch published by Piersma et ai. (1992: Fig. body dimensions are those of the wing according 2). However, there is no reason to extend the to the three different methods (r> 0.87, P< 0.01 width of the coastal strip occupied by Knots to for all three pairs). Since maximum wing length more than 30 km, and the total length of the strip (wing3) is the measurement most commonly in is not 500 km but stretches for 900-1000 km, ta­ use, the following regression equations were deri­ king into account the gap near the Pyasina River ved to convert measurements taken by different mouth. This gives a rough figure of 27 000 km2 methods into maximum wing length and vice Knot breeding habitat at Taimyr. Density estima­ versa: tes are available for 6 sites only (Table 2). Taking the maximal reported densities, the average den­ 2 Wing3 = 31.100 + Wing1 * 0.858; sity will be 1.34 pairs (males) per km , leading to Wing3 = 30.190 + Wing2 * 0.858; an estimate of 72 500 breeding adults. This figure Wingl = 4.404 + Wing3 * 0.927; is closer to the lower limit of the range of 50 000 Wing2 = 5.445 + Wing3 * 0.926, to 500 000 breeding adults on Taimyr, estimated byPiersma et ai. (1992). This means that only a (R2 approximates 0.8 in all these regressions). portion of the world population of C.c. canutus, Since the covariance matrices of males and fe­ currently estimated at 520 000 birds (Piersma et males did not differ (P> 0.7), we used linear dis­ ai. 1992), is breeding at Taimyr Peninsula. criminant analyses. A stepwise procedure showed that the smallest subsets of variables to separate Biogeographic population structure the sexes consisted of combinations of wing and The recoveries and controls received for the total head length, or wing and bill length. The Taimyr Knots occurred in migration seasons and probabilities oferroneous classification (P= 0.249 do not unambiguously prove movements to or for males and P= 0.258 for females) were estima- from Africa. Nevertheless, together with dates of 94 ARDEA 84(1/2), 1996

Table 8. Bill and wing lengths (in mm) of adult male and female Knot Calidris canutus canutus and C.c. islan- dica from Taimyr, Germany (Schleswig-Holstein), Britain (Morecambe BayfThe Wash and Teesmouth), Norway (Balsfjord) and South Africa, measured alive or freshly collected. Shown are samples size (n), mean and S.D. for males and females. Sexing in Schleswig-Holstein was based on plumage colour.

Subspecies/Region Bill length Source

Males Females

n mean SD n mean SD

Calidris canutus canutus Taimyr 38 33.7 1.6 16 35.8 1.5 this study Schleswig-Holstein 440 34.2 1.68 435 35.1 2.1 Prokosch 1988 South Africa 26 34.5 1.0 17 35.9 1.5 R.Summers inpick et a1.1976

Calidria canutus islandica Schleswig-Holstein 109 32.4 1.4 68 33.5 1.6 Prokosch 1988 Morecambe BayIWash 92 32.2 1.92 71 34.0 1.69 A.J.Prater in Dick et al. 1976 Teesmouth 23 31.6 1.56 36 33.1 1.82 Davidson et al. 1986 Balsfjord 49 32.2 1.67 47 33.8 1.95 Davidson et al. 1986

Subspecies/Region Wing length Source

Males Females

n mean SD n mean SD

Calidris canutus canutus Taymir 38 169.0 4.2 15 173.2 3.8 this study Schleswig-Holstein 325 169.4 3.8 348 170.4 4.9 Prokosch 1988

Calidria canutus islandica Schleswig-Holstein 111 172.4 3.6 69 174.8 3.7 Prokosch 1988

migration (see below) and other African and Taimyr-males (Table 8) differs only from mean European recoveries (Dick et al. 1976, 1987; Gro­ bill length of South African winterers (P< 0.05). madzka 1985,1992; Piersma et al. 1992; Schekker­ However, this difference is much less than the dif­ man et al. 1992), they indicate at least a partial mi­ ference between mean bill lengths of Taimyr­ gratory link between Africa and Taimyr. The di­ birds and those of the European-wintering Nearc­ rections of visible spring and postbreeding migra­ tic population usually assigned to subspecies is­ tions of Knots on Taimyr support the idea of their landica, which are shorter billed. Thus, the sugge­ passage through Europe. A comparison of bio­ stion that Taimyr Knots have shorter bills than the metric measurements (Table 8) shows great simi­ majority of birds of the nominate subspecies larity among measurements made at various (Tomkovich 1990, 1992; Piersma et al. 1992) is not points along the flyway. The mean bill length of confirmed by this study. The wing length ofKnots Tomkovich & Soloviev: KNOTS ON TAIMYR, SIBERIA 95 from Taimyr are more similar to those assigned to July and August (Kozlova 1962; Danilov et at. the subspecies canutus than to the subspecies is­ 1984; Estafiev 1991), and Knots do not occur an­ tandica (Table 8). Earlier findings indicating size nually and then only in small numbers along the similarity of Taimyr and Greenland birds (Tom­ Murmansk coast in August and early September kovich 1990, 1992), were probably due to compa­ (Tatarinkova 1982). At Kandalaksha Bay in the risons of small samples of museum specimens. White Sea Knots show up more regularly, with flocks up to 70 birds in August and September Spring migration (Belopolsky et at. 1970). The departure dates from According to observations in western Europe, Taimyr correspond well to dates of passage along Afro-Siberian Knots stay in Schleswig-Holstein Baltic shores. Here adults mainly occur in late for 3-4 weeks and depart late May-early June, July and early August, and juveniles from mid crossing the Baltic Sea in early June (Dick et at. August to late September (Gromadzka 1992; 1987; Prokosch 1988; Piersma et at. 1992). In the Meissner 1992; Piersma et at. 1992). The main de­ same period Knots can be found in varying num­ parture of presumably Knots of the nominate race bers along the Kandalaksha Bay coast, the White from the Wadden Sea to Africa occurs from late Sea, disappearing in the period from 26 May to 10 July to mid September. Juveniles arrive on the June in different years (Belopolsky et at. 1970). At wintering grounds in Mauritania until October ­ the Murmansk Coast of the Kola Peninsula, they early November (Piersma et at. 1992). Postbree­ pass non-stop from 3-16 May to 11 May ­ ding Knots thus seem to overfly west Siberian and 13 June, but not annually, being most abundant in European tundras. This is surprising, since brood­ mid May (Kokhanov & Skokova 1967; Tatarin­ attending males have low body masses (pers. kova 1982). In the mouth of the Nes' River, on the obs.) and would seem to require refuelling areas White Sea coast of Kanin Peninsula, hundreds of somewhere between Taimyr and the Wadden Sea. feeding Knots were recorded 17-20 June 1969 (Zubtsovsky & Ryabitsev 1976). In NE Yamal several hundred Knots were found feeding on CONCLUSIONS boggy tundra on 3 to 10 June 1990, and flocks up to 70 Knots were passing northward and northe­ Our study confirms that Knots breeding at Taimyr astward in the first half of June in 1992-94, but Peninsula belong to the nominate subspecies ca­ not in 1988-89 and 1991 (Ryabitsev et at. 1995). nutus, which migrates along the coast of western This schedule of spring migration through nort­ Europe probably to winter in West Africa. Howe­ hern Europe agrees with the arrival to Taimyr on ver, we can not rule out the possibility that some 5 to 21 June and passage until 24 June. Knots from Taimyr winter in western Europe. If the world population of the nominate subspecies Post-breeding migration is indeed much larger than the numbers breeding The departure of adult Knots from Taimyr occurs on Taimyr, unknown breeding areas may exist so­ from early July to almost mid-August. Migration mewhere in Siberia (Tornkovich 1990, 1992; ofjuvenile birds lasts for about a month, from 5-9 Piersma et at. 1992). The spring records along the August until the first days of September. The wi­ Polar Circle and further south in Middle Siberia dely known report ofBirula (1907, in Pleske 1928) suggest a possible migration route to these bree­ about the mass westward passage of adult Knots ding grounds. in the Middendorff Bay, northwestern Taimyr, du­ ring the night of 28/29 August 1900 appears a mi­ ACKNOWLEDGEMENTS stake due to wrong aging. Only a few records of 1-8 Knots are known in This study was carried out in one of the most remote the region between Taimyr and the White Sea in field camps of the International Arctic Expedition of 96 ARDEA 84(1/2), 1996 the Institute for Ecology and Evolution, Russian Aca­ 1984. [Birds of Yamal.] Nauka, Moscow (in Rus­ demy of Sciences, and was only possible because of fi­ sian). nancial and logistic support of the expedition organis­ Davidson N.e. &T Piersma 1992a. Introduction. Wa­ ors, Academician Professor E.E.Syroechkovski and his der Study Group Bull. 64, Suppl.: 9-13. expedition staff, especially N.Y. Vronsky, E.E. Sy­ Davidson N.C. & T. Piersma 1992b. The migration of Knots: conservation needs and implications. Wader roechkovski Jr, M.M. Zabelin, M.G. Sinitsyn and Study Group Bull. 64, Suppl.: 198-209. A Abolits. Observations of the expedition participants Davidson N.e., K-B. Strann, N.I. Crockford, P.R. Evans, both from our Knipovich Bay expedition team I. Richardson, L.I. Standen, DJ. Townshend, (0. Hilden, P. Yesou, G.Th. de Roos, E.E. Syroech­ J.D. UUley, J.R. Wilson &AG. Wood 1986. The ori­ kovski Jr, E.G. Lappo, AY. Rybkin and Y.O. Yakovlev) gins of Knots Calidris canutus in arctic Norway in and from other camps (Y.N. Karpov, E.E. Syroech­ spring. Ornis Scand. 17: 175-179. kovski Jr, 1.1. Chupin, AY. Rybkin and TY. Sviridova) Davis I.e. 1986. Statistics and data analysis in geology. were of great help for the study. Y1. Chernov, P. Chyla­ John Wiley & Sons, New York. recki, H. Hotker, P.-E. Jonsson, W. Kania, E.G. Lappo, Deev AD. 1972. [Asymptotic expansion of discrimi­ A Moroz, T Piersma, A.ARomanov, A.Y. Rybkin, H. nant analysis statistics' W, M, W* distribution.] In: [Statistical methods of classification 3: 6-51.] Schekkerman, E.E. Syroechkovski Jr, K van Dijk & Moscow State Univ. Press, Moscow (in Russian). AE. Volkov, not explicitly cited in the text, kindly pro­ Dick WJ.A, M.W Pienkowski, M. Waltner & vided unpublished information. Collections of the Na­ C.D.T Minton 1976. Distribution and geographi­ tural History Museum in Tring, of Zoological Institute cal origins of Knot Calidris canutus wintering in in St.-Petersburg, and of Zoological Museum in Mos­ Europe and Africa. Ardea 64: 22-47. cow were used as an additional source of information. Dick WJ.A, T Piersma & P. Prokosch 1987. Spring We thank R.P. Pt1s-Jones and Y.M. Loskot, curators of migration of the Siberian Knots Calidris canutus these collections. We value the comments on the manu­ canutus: results of a co-operative Wader Study script made by Theunis Piersma, Meinte Engelmoer Group project. Ornis Scand. 18: 5-16. and an anonymous referee. Estafiev AA 1991. [Fauna and ecology of waders in Bolshezemelskaya tundra and Yugor peninsula.] Nauka, Leningrad (in Russian). Frodin P., F. Haas & A. Lindstrom 1994. Bird migra­ REFERENCES tion at Sibiryakov Island, Taimyr, Siberia in early summer 1992. Rep. Dept. Ecology, Lund Univer­ Afifi AA & S.E. Azen 1979. Statistical Analysis. A sity, Lund. Computer Oriented Approach. Academic Press, Green G.H. 1980. Total head length. Wader Study New York. Group Bulletin 29: 18. Ahrens H. & J. Lauter 1981. Mehrdimensionale Varian­ Gromadzka J. 1985. [The Red Knot Calidris canutus.] zanalyse. Akademie-Verlag, Berlin. In: Viksne YA & K.A Mikhelson (eds) [Migra­ Andreev B.N. 1987. The birds of Vilyui Basin. Knizh­ tions of birds of eastern Europe and northern Asia: noye Izdatelstvo, Yakutsk (in Russian). Gruiformes-Charadriiformes: 221-229.] Nauka, Belopolsky L.O., Y.Y. Bianki & Y.D. Kokhanov 1970. Moscow (in Russian). [Materials on ecology of waders (Limicolae) of Gromadzka J. 1992. Knots on the Polish Baltic coast. the White Sea.] In: Stegmann B.K (ed.) Ann. Kan­ Wader Study Group Bull. 64, Suppl.: 161-166. dalaksha State Nat. Res. 8: 3-84. Murmansk Pu­ Hotker H. 1995. Avifaunistical records of the expedi­ blishing House, Murmansk (in Russian). tions to Taimyr in the years 1989, 1990 and 1991. Birula A 1907. [Notes on the life of birds on the polar In: P. Prokosch & H. Hotker (eds). Faunistik und coast of Siberia.] Trans. Acad. Sci. VIII, phys. Naturschutz auf Taimyr, Expeditionen 1989-1991: math. sect. 18(2): 1-157 (in Russian). 34-89. Corax 16, Sonderheft. Boyd H. 1992. Arctic summer conditions and British Karpov Y.N., E.E. Syroechkovski, Jr., TY. Sviridova, Knot numbers: an exploratory analysis. Wader D. Frohlich & Y.F. Dorogov in press. [Bird fauna of Study Group Bull. 64, Suppl.: 144-152. the area ofthe Tonskoe and Labas Lakes (North-Si­ Chernov Y1. 1985. The Living Tundra. Cambridge berian Lowland).] In: Rogacheva E.Y. (ed.) [Birds University Press, Cambridge. ofTaimyr and the Putorana Mountains.] Inst. Ecol. Cramp S. & KE.L. Simmons (eds) 1983. The birds of & Evol., Russian Acad. Sci., Moscow (in Russian). the Western Palearctic, 3. Oxford Univ. Press, Ox­ Kokhanov Y.D. & N.N. Skokova 1967. [Bird fauna of ford. the Aynovy Isles.] Ann. Kandalaksha State Nat. Danilov N.N, Y.N. Rizhanovsky & Y.K Ryabitsev Res. 5: 185-267 (in Russian). Tomkovich & Soloviev: KNOTS ON TAIMYR, SIBERIA 97

Kozlova E.v. 1962. [Fauna of the USSR. Birds. Vol.2, Rose1aar C.S. 1983. Subspecies recognition in Knot issue 1, part 3.] Acad. Sci. USSR, Moscow & Le­ Calidris canutus and occurrence of the races in ningrad (in Russian). Western Europe. Beaufortia 33: 97-109. Leonovich v.v. & S.M. Uspensky 1965. [Climate pe­ Ryabitsev v.K., V.V.Tarasov & AK.Iskandarov. [To culiarities and bird life in the Arctic.] In: Schwarz distribution of birds on north-eastern Yamal.] In: S.S. & G.P. Pomerantsev (eds) [Ecology of verte­ Ryabitsev v.K. (ed.) [Materials to distribution of brate animals of the extreme North: 141-148.] birds on the Urals, in Priural'e and in West Siberia: Sverdlovsk (in Russian). 66-68.] Ural Branch Russian Acad. Sci., Ekaterin­ Leonovich v.v. & B.N. Veprintsev 1980. [Materials on burg (in Russian). the biology ofKnot.] In: Flint V.E. (ed.) [New data SAS Institute 1987. SAS/STAT guide for personal in the study of the biology and distribution of wa­ computers (6th edition). SAS Institute, Cary. ders: 152-153.] Nauka, Moscow (in Russian). Scalon W.-N. 1935. Les oiseaux du sud du Taimir, 2 ­ Meissner W. 1992. Knots autumn migration in the wes­ Le passage. Gerfaut 3: 201-217. tern part of the Gulf of Gdansk, Poland: prelimi­ Schekkerman H., P.L. Meininger & R.H.D. Lambeck nary results. Wader Study Group Bull. 64, Suppl.: 1992. Knots in the Delta area, southern Nether­ 167-171. lands. Wader Study Group Bull. 64, Suppl.: 175­ Morrison R.I.G. 1975. Migration and morphometries of 181. European Knot and Turnstone on Ellesmere Is­ Schekkerman H. & M.W.I. van Roomen. 1995. Bree­ land, Canada. Bird-Banding 46: 290-301. ding waders at Pronchishcheva Lake, northeastern Morrison R.I.G. & N.C. Davidson 1990. Migration, Taimyr, Siberia, in 1991. WIWO report 55, Zeist. body condition and behaviour of shorebirds during Sdobnikov V.M. 1959. [Waders of northern Taimyr.] spring migration at Alert, Ellesmere Island, Ann. Agricult. Inst. Extreme North 9: 184-207 (in N.W.T. In: Harington c.R. (ed.) Canada's missing Russian). dimension. Science and history in the Canadian Spiekman H. & N. Groen 1993. Breeding performance Arctic Islands: 544-567. Canadian Museum of Na­ of arctic waders in relation to lemming densities, ture. Ottawa. North-East Taimyr, Siberia, 1992. WIWO-Report Piersma T. & N.C. Davidson (eds) 1992. The migration of 33, Zeist. Knots. Wader Study Group BulL 64, SuppL: 1-210. Soloviev M.Y. & P.S.Tomkovich. 1995. Biometrics of Piersma T., L. Zwarts & I.H. Bruggemann 1990. Beha­ Sanderlings Calidris alba from the Taimyr. Rin­ vioural aspects of the departure of waders before ging & Migr. 16: 91-99. long-distance flights: flocking, vocalization, flight Syroechkovski Jr E.E. & E.G. Lappo. 1994. [Data on paths and diurnal timing. Ardea 78: 157-184. fauna and ecology of birds of the Izvestiy Tsik Is­ PiersmaT., P. Prokosch & D. Bredin 1992. The migration lands and Sverdrup Island.] In: Rogacheva system ofAfro-Siberian Knots Calidris canutus ca­ E.V. (ed.) [Arctic tundras of Taimyr and Kara Sea nutus. Wader Study Group Bull. 64, Suppl.: 52-63. islands: nature, fanna and conservation problems, Pleske T. 1928. Birds of the Eurasian tundra. Mem. 1: 111-151.] Inst. Ecol. & Evol., Russian Acad. Boston Soc. Nat. Hist. 6: 107-485. Sci., Moscow (in Russian). Priklonsky S.G. 1960. [Use of automatic "luchock"­ Svensson L. 1984. Identification Guide to European traps for bird catching.] Zool.Zhurnal 39: 623-624 Passerines. Stockholm. (in Russian). Tatarinkova I.P. 1982. [On wader migration in the Va­ Prokosch P. 1988. Das Schleswig-Holsteinsche Watten­ ranger Fjord.] In: V.N. Karpovich (ed.) [Bird eco­ meer a1s Fruhjahrs-Aufenthaltsgebiet arktischer logy and morphology at extreme north-west of the Watvoge1-Populationen am Beispiel von Kiebitz­ USSR: 98-108.] Moscow (in Russian). regenpfeifer (Pluvialis squatarola, L. 1758), Knutt Tomkovich P.S. 1990. [Analysis of geographical varia­ (Calidris canutus, L. 1758) und Pfuhlschnepfe bility in Knot Calidris canutus (L.).] Bull. Mos­ (Limosa lapponica, L. 1758). Corax 12: 274-442. cow Soc. Naturalists, BioI. Div. 95: 59-72 (in Rus­ Rogacheva H.V. 1988. [The birds of Central Siberia: sian) distribution, numbers, zoogeography.] Nauka, Tomkovich P.S. 1992. An analysis of the geographic Moscow (in Russian). variability in Knots Calidris canutus based on mu­ Rogacheva H. 1992. The birds of central Siberia. seum skins. Wader Study Group Bull. 64, Suppl.: Druck- und Verlagsges., Husum. 17-23. Romanov AA in press. [Avifauna of the Central part Tomkovich P.S. & M.Y. Soloviev 1994. Site fidelity in of the Putorana Plateau.] In: Rogacheva E.V. (ed.) High Arctic breeding waders. Ostrich 65: 174-180. [Birds of Taimyr and the Putorana Mountains.] Tomkovich P.S. & N.V. Vronsky 1988a. [Avifauna and Inst. Ecology & Evolution, Russian Acad. Sci., bird populations of the arctic tundras on the Khari­ Moscow (in Russian). ton Laptev Coast (northwestern Taimyr).] In: Rog- 98 ARDEA 84(1/2), 1996

acheva H.V. (ed.) [Contributions to the fauna of Wilkinson L. 1990. SYSTAT: The System for Statistics. Central Siberia and adjacent regions of Mongolia: Evanston, IL.: SYSTAT, Inc. 5-47.] Inst. Eco!. & Evo!., Russian Acad. Sci. Wymenga E., M. Engelmoer, C.J. Smit & T.M. van USSR, Moscow (in Russian). Spanje 1990. Geographical breeding origin and Tomkovich P.S. & N.V. Vronsky 1988b. [Bird fauna of migration of waders wintering in West Africa. Ar­ the Dickson area.] Arch. ZooI. Mus. Moscow State dea 78: 83-112. Univ. 26: 39-77 (in Russian). Zubtsovsky N.E. & v.K. Ryabitsev 1976. [New data on Tomkovich P.S. & N.V. Vronsky 1994. [The birds of birds of Kanin Peninsula.] Ornitologiya 12: 128­ the lower reaches of the Uboinaya River, (North­ 131 (in Russian). Western Taimyr).] In: Rogacheva E.V. (ed.) [Arc­ tic tundras ofTaimyr and Kara Sea islands: nature, fauna and conservation problems, 1: 161-206.] Inst. Eco!. & Evo!., Russian Acad. Sci., Moscow SAMENVATTING (in Russian). Tomkovich P.S., M.Y. Soloviev & E.E. Syroech­ In twee series van drie opeenvolgende zomers (1982­ kovsky Jr. 1994. [Birds of arctic tundras of nort­ 84 en 1990-92) werd de broedbiologie van Kanoet­ hern Taimyr, Knipovich Bay area.] In: Rogacheva strandlopers Calidris canutus in het hoogarctische E.V. (ed.) [Arctic tundras of Taimyr and Kara Sea kustgebied van het Taimyr schiereiland in Noord-Sibe­ islands: nature, fauna and conservation problems rie onderzocht. Gegevens over de biometrie van op het 1: 44-110.] Inst. Eco!. & EvoI., Russian Acad. Sci., nest gevangen en verzamelde vogels, trekwaamemin­ Moscow (in Russian). Tugarinov AY. & AI. Tolmachev 1934. [Materials for gen en recente terugmeldingen van in Taimyr geringde the avifauna of eastern Taimyr.] Ann. Polar broedvogels worden in dit artikel gecombineerd met Comm. USSR Acad. Sci. 16: 5-47 (in Russian). een samenvatting van aIle gepubliceerde en ongepubli­ Underhill L.G., M. Waltner & R.w. Summers 1989. ceerde gegevens over de broed-verspreiding van Three-year cycles in breeding productivity of Kanoetstrandlopers in Noord-Siberie. Op basis van een Knots Calidris canutus wintering in southern Af­ discriminant analyse van de biometrische verschillen rica suggest Taimyr Peninsula provenance. Bird tussen mannetjes en vrouwtjes werd een formule ont­ Study 36: 83-87. wikkeld om op het nest gevangen vogels te sexen op Underhill L.G., R.P. PIts-Jones, E.E. Syroechkov­ grond van snavel- en vleugellengte. AIle verzamelde ski, Jr., N.M. Groen, V. Karpov, H.G. Lappo, gegevens ondersteunen de in de literatuur geformu­ M.W.J. van Roomen, A Rybkin, H. Schekkerman, H. Spiekman & R.W. Summers 1993. Breeding of leerde hypothese dat Kanoetstrandlopers van Taimyr waders (Charadrii) and Brent Geese Branta berni­ tijdens de voor- en najaarstrek in West- Europa verblij­ cia bernicia at Pronchishcheva Lake, northeastern Yen. Het lijkt erg waarschijnlijk dat deze populatie in Taimyr, Russia, in a peak and a decreasing lem­ de kustgebieden van West- Afrika overwintert, hoewel ming year. Ibis 135: 277-292. dat nog steeds niet met een directe terugmelding bewe­ Von Middendorff AT. 1853. Reise in den aussersten zen is. Een samenvatting van de gegevens over de Norden und Osten Sibiriens, Wahrend der Jahre dichtheden aan broedparen in het bekende broedareaal 1843 und 1844 Saugetiere, Vogel und Amphibian. op Taimyr bevestigt de veronderstelling dat slechts Band II. Teil 2. St.Petersburg. 72 500 van de 500 000 in West-Afrika overwinterende Vronsky N.V. 1977. [Spring passage of birds in the Kanoetstrandlopers op het Taimyr schiereiland als middle part of Central Siberia.] In: Rogacheva E.V. (ed.) [BioI. resources, biocenosises and hun­ broedparen gevonden kunnen worden. Dit suggereert ting economy in taiga of Turukhansk: 139-146.] dat er in Siberie nog een onbekend broedgebied ligt dat Central Lab. for Nature Conservation, Moscow (In op ontdekking wacht. (TP) Russian). Whitfield D.P. & IJ. Brade 1991. The breeding behavi­ Received15 November 1994, accepted 19 February 1996 our ofthe Knot Calidris canutus. Ibis 133: 246-255. Corresponding editor: Johan van Rhijn