Siberian waders are mainly long-distance migrants, many of which follow the coastal flyways of Western Europe and Northern Africa, or migrate along the East Asian coasts (Veen et al. Reference Veen, Yurlov, Delany, Mihantiev, Selivanova and Boere2005, Davidson and Stroud Reference Davidson, Stroud, Boere, Galbraith and Stroud2006, Delany et al. Reference Delany, Scott, Dodman and Stroud2009). Others migrate inland across Western Asia, and these can be assigned to three flyways: (a) the Black-Sea/Mediterranean flyway via Western Asia, Eastern Europe and the Caucasus region to the Mediterranean Basin and West Africa, (b) the West-Asian-East-African flyway via Central Asia to the Middle East, Southern Asia and Eastern Africa and (c) the Central Asian flyway via Central Asia to the Indian Subcontinent (Stroud et al. Reference Stroud, Davidson, West, Scott, Haanstra, Thorup, Ganter and Delany2004, Delany et al. Reference Delany, Scott, Dodman and Stroud2009). In Central Asia, there are relatively few wetlands that provide the opportunity for refuelling. One of the largest wetland complexes of Central Kazakhstan is situated in the Tengiz-Korgalzhyn region (c. 49.5–51°N, 68–71°E). This region has been shown to hold large numbers of waterbirds (Krivitskii et al. Reference Krivitskii, Khrokov, Volkov and Zhulii1985, Eichhorn Reference Eichhorn2001, Koshkin and Koshkina Reference Koshkin and Koshkina2003, Gavrilov and Gavrilov Reference Gavrilov and Gavrilov2005, Schielzeth et al. Reference Schielzeth, Eichhorn, Heinecke, Kamp, Koshkin, Koshkin and Lachmann2008), but comprehensive estimates of wader, gull and tern population sizes are still lacking.
Accurate estimates of bird numbers from individual wetlands are highly relevant for the implementation of wetland conservation programmes. They are needed to facilitate effective conservation of species of global concern and to prioritise local conservation efforts (Wetlands International 2006). To maximise conservation benefits, the development and maintenance of a network of refuelling sites along migration routes is required (Boere et al. Reference Boere, Galbraith and Stroud2006). Recognition of such sites under the Ramsar convention and as Important Bird Areas (IBAs) can provide valuable means of safeguarding key sites for waterbirds (Frazier Reference Frazier1999, BirdLife International 2001, Ramsar Convention Secretariat 2006). Both depend on sufficient information on the number of birds using particular sites. In Kazakhstan, a total of 121 IBAs have been identified recently, covering almost 150,000 km2, equivalent to 5.5% of the country area (Sklyarenko et al. Reference Sklyarenko, Welch and Brombacher2008). Eight of these IBAs are situated in the Tengiz-Korgalzhyn region (Table 1). However, further data are needed to clarify if all the important wetlands are covered by the IBA network.
Here we provide recent population size estimates and phenology data for waders and larids (Charadiiformes) for the Tengiz-Korgalzhyn region. A list of potential IBAs for this region has been published previously (Schielzeth et al. Reference Schielzeth, Eichhorn, Heinecke, Kamp, Koshkin, Koshkin and Lachmann2008) but was based on other groups of waterbirds (mainly waterfowl). By expanding on waders and larids and including additional data from recent years, we update that former list and analyse how regularly individual sites hold significant numbers of waterbirds, in order to identify sites of high conservation priority in one of Central Asia’s most important wetland complexes.
Material and methods
The study region encompasses an area of about 180 × 150 km some 120 km southwest of the Kazakh capital Astana. The Korgalzhynskij zapovednik, a state nature reserve (IUCN category 1a), constitutes the core of the study area. It was extended in December 2008 to include not only the Lakes Bolshoi Tengiz, Malyi Tengiz and Lake Korgalzhyn, but also large areas of steppe habitats. The lakes of the zapovednik are registered as a Ramsar site (‘Tengiz-Korgalzhyn Lake System’, 2,589 km2, Sklyarenko et al. Reference Sklyarenko, Welch and Brombacher2008) and since 2008 the zapovednik is part of the Saryarka World Heritage Site (UNESCO 2008). In addition to the zapovednik area itself, another seven IBAs have been identified in the Tengiz-Korgalzhyn area, totalling 837 km2 (Sklyarenko et al. Reference Sklyarenko, Welch and Brombacher2008, Table 1).
The region is characterized by pristine steppe grassland and dominated by the saline Lake Tengiz. It comprises a very large complex of saline and freshwater lakes. Due to low precipitation and high evaporation, lakes tend to shrink in size during summer and some dry up completely every year. Fluctuating water levels provide extensive areas of shallow water and large mudflats that are available to waders stopping over on migration. South of the Tengiz-Korgalzhyn region lies the extensive Betpak-dala semi-desert, a region lacking any significant areas of wetland. Hence, the Tengiz-Korgalzhyn wetland complex constitutes an important series of refuelling sites for waterbirds before (spring) or after (autumn) crossing this barrier.
Most of the data analysed here were collected together with data on other waterbird species analysed by Schielzeth et al. (Reference Schielzeth, Eichhorn, Heinecke, Kamp, Koshkin, Koshkin and Lachmann2008), and we refer to that paper for a more detailed description of survey methods including maps showing the spatial-temporal distribution of survey counts in 1999–2004. However, by adding data from four more years, the present paper covers a study period of 10 years from 1999 to 2008. Surveys in 2005–2008 focussed more on spring, because this season had been less well covered in the years before. We also included results from dedicated surveys for two species of special conservation concern, Sociable Lapwing Vanellus gregarius (R.D. Sheldon and J. Kamp, unpubl. data) and Black-winged Pratincole Glareola nordmanni (Kamp et al. Reference Kamp, Koshkin and Sheldon2009). Both species were not sufficiently covered in our general wetland surveys, primarily because they are not confined to wetland habitats. The main focus of the survey work was to count the number of individuals, but for some species we made additional efforts to record the numbers of juveniles and adults separately.
Calculation of local population sizes
Estimates were calculated from counts at individual sites. The temporal resolution was set to monthly thirds (i.e. day 1–10, 11–20 and 21–30/31 of each month). We analysed the data separately for the months April to mid-June (‘spring’) and end-June to October (‘autumn’). This separates the year into approximately a pre-breeding and a post-breeding phase. Waders and larids vacate the area completely in winter (December to February) when all lakes are frozen. Numbers of waterbirds are generally very low in November and March.
As outlined in Schielzeth et al. (Reference Schielzeth, Eichhorn, Heinecke, Kamp, Koshkin, Koshkin and Lachmann2008), we calculated two estimates of the local population for all species. Estimate one (Est1) is the highest number of individuals counted within a monthly third in any of the ten years considered. It comprises summed data from different sites, assuming that changes in distributions within these 10–11 days are negligible. Estimate two (Est2) is the largest sum of average site counts (averaged between years) within a monthly third. This yields better coverage of the study region, since different parts of the study area were surveyed in different years. More formally, Est1 was calculated as the maximum of Njk with Njk calculated as
for every monthly third in every year, where cijk is the count for site i in year j and monthly third k. Est2 was calculated as the maximum of Nk with Nk calculated as
for every species and every monthly third, where aik is the number of birds at site i in monthly third k averaged from all years for which data were available.
We present a final estimate in ranges of rounded figures between the two estimates Est1 and Est2. Since we do not have any information on staging duration and migratory turn over, all estimates refer to peak staging numbers. True numbers of waders passing through during spring and autumn migration are certainly much higher. We rounded numbers below 100 to the nearest 5, below 1,000 to the nearest 10, below 10,000 to the nearest 100 and above 10,000 to the nearest 1,000. Non-zero estimates < 5 were set to 0–5.
To give an overview of the local wader and larid breeding fauna, we present the current breeding status for all species. Breeding surveys, however, were not the focus of the study.
Comparison with flyway population estimates
We compared our local population estimates to the estimates for the relevant flyway populations as published by Wetlands International (2006) and assigned flyway populations according to breeding and wintering ranges given therein. We considered populations that were covered either under ‘Central Asia’, ‘SW Asia’, ‘W Asia’ or ‘Kazakhstan’ or a combination of breeding grounds in ‘Western Siberia’ and wintering ground in ‘East Africa’, ‘Middle East’ or ‘S Asia’, since birds of these populations are likely to pass through the study area. Occasionally, more than one relevant flyway population had to be considered. In these cases we compared our estimates to the total of all relevant flyway estimates combined. We used mid-range values to calculate the proportion of the Tengiz-Korgalzhyn population relative to the total flyway population.
Identification of key sites
We identified individual sites within our study area that qualified as potential IBA and/or Ramsar sites. The relevant IBA criteria are: (A4i) the site supports more than 1% of the flyway populations of a congregatory waterbird on a regular basis and (A4iii) the site supports more than 20,000 waterbirds of one or more species on a regular basis (Heath and Evans Reference Heath and Evans2000). IBA criterion A4i is equivalent to Ramsar criterion 6, while IBA criterion A4iii is equivalent to Ramsar criterion 5 (Ramsar Convention Secretariat 2006). Since these criteria are not limited to Charadriiformes, we included data on other species of waterbirds (see Schielzeth et al. Reference Schielzeth, Eichhorn, Heinecke, Kamp, Koshkin, Koshkin and Lachmann2008, updated for the years 2005–2008). Besides criteria A4i and A4iii, criterion A1 (the occurrence of significant numbers of globally threatened species) is, among Charadriiformes, applicable for the ‘Critically Endangered’ Sociable Lapwing. However, detailed information on key breeding and staging sites of this species will be published elsewhere (R. D. Sheldon and J. Kamp, in prep.).
To determine if high numbers of waterbirds occur on a regular basis, we calculated the number of years, in which one of the criteria was fulfilled and the number of years in which a particular site was visited at a relevant time of the season. The latter was done by counting the number of years a site was visited in a monthly third for which the criterion was reached in at least one year. We consider sites that fulfilled at least one of the criteria in more than one year and in at least half the years of visits as fulfilling the criteria ‘on a regular basis’ and those that fulfilled the criteria in less than half of the years as ‘irregular’. Sites that fulfilled the criteria in one year only (with one or two visits) were classified as ‘data-deficient’.
The Tengiz-Korgalzhyn region serves as an important stopover site for waders during the pre-breeding as well as during the post-breeding migratory seasons (Tables 2 and 3). For many wader species (among them the most numerous ones, Red-necked Phalarope Phalaropus lobatus and Ruff Philomachus pugnax), numbers in spring were substantially higher than in autumn. The estimated total of waders, gulls and terns in the study area in spring amounted to 920,000–1,020,000 birds while numbers in summer and autumn were substantially lower totalling 250,000–310,000 individuals. The general pattern of higher spring numbers in many species did not change when limiting the analysis to survey years 1999–2004. A number of species, however, occur mainly on post-breeding migration (Figure 1).
a Since the coverage was incomplete and a dedicated survey of the breeding population was conducted in 2006 (Kamp et al. Reference Kamp, Koshkin and Sheldon2009), we used twice the number of breeding pairs as an estimate for the spring population.
b Heuglin’s Gull Larus heuglini heuglini and Baraba Gull Larus heuglini barabensis are recognised as conspecifics (under the name Heuglin’s Gull Larus heuglini) in Wetlands International (2006), but are currently under taxonomic review by BirdLife International. Independent of the decision we treat them as separate taxa, since the Baraba Gull is a widespread breeding bird and Heuglin’s Gull is a passage migrant in our study region, and both are identifiable in the field.
c In May–June 2000 we counted a total of at least 1,100 pairs. We used twice the number of breeding pairs as an estimate for the spring population.
Most species for which sufficient data were available showed a high prevalence of adults in June/July and a strong dominance of juveniles in September/October (Figure 2). Notable exceptions were Pied Avocet Recurvirostra avosetta and Black-tailed Godwit Limosa limosa, for which adults dominated even in late summer. These two species show large moulting aggregations in the study region.
Based on a comparison with the total flyway population numbers, the Tengiz-Korgalzhyn region is of significant importance for Red-necked Phalaropes and Ruffs. These species were present in the area with 41% and 13%, respectively, of their total flyway population estimates (Table 4). Dunlin Calidris alpina, Little Stint Calidris minuta, Spotted Redshank Tringa erythropus and Black-tailed Godwit (the latter classified as ‘Near Threatened’) occurred with about 5–6% of the their flyway population estimates, while other migrant species showed lower proportions. Pallas’s Gull Larus ichthyaetus breeds with at least 1,715 pairs (data from 2000), which is equivalent to 5% of the individuals of the Central Asian population. Sociable Lapwing (‘Critically Endangered’) and Black-winged Pratincole (‘Near Threatened’) used the area in significant numbers as well, with up to 16% and 6%, respectively, of their world populations.
There were 29 sites that held more than 1% of the flyway population for any species of Charadriiformes (excluding Sociable Lapwing). Including data on other species of waterbirds, we identified 93 individual sites that fulfilled IBA-criteria A4i and/or A4iii at least once during our study period (Figure 3, Table 5, Appendix). Forty-four (47%) of these sites held high numbers of waterbirds on a regular basis, while 47 (51%) have to be considered data-deficient for an assessment of regularity. Only two sites showed high numbers in less than 50% of all years of visits and are thus possibly of high importance for waterbirds only in some years.
Our data show the outstanding importance of the Tengiz-Korgalzhyn wetlands for waders, gulls and terns. Ruff and Red-necked Phalarope in particular show very high absolute numbers as well as high proportions relative to the flyway population. Although numbers of most other species are lower than those of many species of waterfowl (Schielzeth et al. Reference Schielzeth, Eichhorn, Heinecke, Kamp, Koshkin, Koshkin and Lachmann2008) and comprise lower proportions of the relevant flyway populations, the region is an important staging and breeding site for many species of Charadriiformes. For some species, numbers were much higher in spring than in summer/autumn, which may be indicative of loop migration. In contrast, the phenology of waterfowl in the study area was biased towards the post-breeding period (Schielzeth et al. Reference Schielzeth, Eichhorn, Heinecke, Kamp, Koshkin, Koshkin and Lachmann2008).
The region’s many water bodies of highly variable salinity produce a variety of benthic and epibenthic prey species principally available to waders. Larvae and pupae of alkali flies Ephydra sp. and long-legged flies Dolichopus sp. comprise most of the macrozoobenthos in saline lakes, while several species of Chironomidae larvae provide a rich food source in brackish and freshwater lakes (Eichhorn Reference Eichhorn2001). Although occurring more sporadically, mass concentrations of Brine Shrimp Artemia salina can attract huge numbers of waders, particularly phalaropes, to highly saline lakes and pools (Krivitskii et al. Reference Krivitskii, Khrokov, Volkov and Zhulii1985). Most of these sites are of little interest to human exploitation and are left undisturbed. Power line casualties of Red-necked Phalaropes have been noted (own observations), but power lines are relatively rare around lakes holding the highest numbers of waders.
The Tengiz-Korgalzhyn region was for a while one of the last known breeding sites of Sociable Lapwing (Eichhorn and Heinicke Reference Eichhorn and Heinicke2000, Eichhorn and Khrokov Reference Eichhorn and Khrokov2002), whose worldwide population had been estimated as low as 600–1,800 individuals (Wetlands International 2002). Extensive surveys from 2004 to 2008 suggested about 200 pairs currently breeding in the study area (R. D. Sheldon and J. Kamp, unpublished data). The new figures, together with data from other surveys in Kazakhstan have been used to update the world population estimate for this species to 5,600 breeding pairs, equalling 11,200 mature individuals (Sheldon et al. Reference Sheldon, Grishina, Kamp, Khrokov, Knight and Koshkin2006).
The Black-winged Pratincole is another locally breeding wader species that has a stronghold in the Tengiz-Korgalzhyn region. A systematic survey of Black-winged Pratincole colonies has revealed c. 1,500 pairs in the Tengiz-Korgalzhyn region (Kamp et al. Reference Kamp, Koshkin and Sheldon2009). Both Sociable Lapwing and Black-winged Pratincole show a preference for heavily grazed steppe swards close to settlements. This makes trampling by livestock a potentially important cause of clutch loss (Watson et al. Reference Watson, Wilson, Koshkin, Sherbakov, Karpov, Gavrilov, Schielzeth, Brombacher, Collar and Cresswell2006). The same risk may apply to other species that prefer to nest in the surroundings of settlements (e.g. Caspian Plover Charadrius asiaticus, Northern Lapwing Vanellus vanellus).
Most gulls and Sterna terns, among them the Eurasian steppe biome-restricted Pallas’s Gull, are colonial breeders in the Tengiz-Korgalzhyn region. Most of the known colonies are situated on islands of lakes outside the zapovednik but within IBAs. There does not seem to be any immediate danger for these colonies, although they should be considered vulnerable to disturbance. Breeding of Chlidonias terns occur over a much wider area and without dedicated surveys, complete coverage is difficult to achieve.
Including all species of waterbirds, we identified 93 individual sites that fulfilled IBA criteria A4i or A4iii (but see discussion on regularity below). These IBA criteria are equivalent to Ramsar criteria 6 and 5, respectively, meaning that these sites would potentially deserve Ramsar status, too. Although about half of these sites require more data to verify that the criteria are fulfilled on a regular basis, the great majority of sites that have been visited regularly hold significant wader and larid numbers on a regular basis, while only two sites were found to hold significant numbers in less than half of the years of visits (Table 5). Assuming that this sample is representative, it is very likely that most of the data-deficient sites fulfil the regularity condition. Not all potential Ramsar and/or IBA sites are currently protected. Forty-six sites (49%) are situated within the protected zapovednik zone, while 19 (20%) belong to IBAs outside the zapovednik (Figure 3, Table 5). The remaining 28 sites (30%) have not yet been identified as IBAs or Ramsar sites nor do they enjoy any national status of protection. This shows that there is a need for further conservation efforts also outside the current IBA network.
Since our surveys were limited in coverage due to logistical limitations, we may have missed the peaks of migration for some species and sites. Hence, it is likely that some additional sites would fulfil criteria A4i or A4iii on a regular basis, if the survey data were more complete. Furthermore, due to varying water levels between seasons some individual sites may be best considered as subunits of larger sites, since waders may use shallow lakes in wet years but deeper lakes in dry years when shallow lakes dry out completely. Therefore, we advocate a designation of larger IBAs as was done during the recent designation of IBAs in Kazakhstan (Sklyarenko et al. Reference Sklyarenko, Welch and Brombacher2008). However, since the current IBAs do not cover all relevant sites (Figures 3 and 4), we list all potentially relevant sites in the Appendix. Based on these data, we advise the designation of a new IBA southwest of Korgalzhyn, which could comprise a cluster of important sites (sites 20–21, 44, 48, 52, 65, 68, 72–73, 76, 86, 91). Furthermore, it is necessary to consider the sites in the north of the region (particularly important for geese) as one or several additional IBA. Since only the zapovednik is considered a Ramsar site, but many important wetlands exist outside the zapovednik (Figure 3), an extension of this Ramsar site would also be advisable.
Overall, the Tengiz-Korgalzhyn region is of similar importance for migrating waders as it is for waterfowl. Although significant flyway proportions are reached by fewer species compared to waterfowl, the area is certainly one of the key stopover sites for northern-breeding waders on the Central Asian flyway. Moreover, the region hosts notable concentrations of species typically found in the steppe biome like Black-winged Pratincole (‘Near Threatened’), Pied Avocet, Sociable Lapwing (‘Critically Endangered’), Black-tailed Godwit (‘Near Threatened’), Slender-billed Gull Larus genei, Pallas’s Gull and White-winged Tern Chlidonias leucopterus. We suggest this set of species along with the most abundant Nordic migrants (i.e. Red-necked Phalarope and Ruff) should be considered as the target species for the conservation of waders, gulls and terns in the Tengiz-Korgalzhyn region. To maximise conservation benefits, more sites should be considered for IBA status given the importance of the wetland complex to Charadriiformes and other waterbirds.
The supplementary materials for this article can be found at journals.cambridge.org/bci
We are grateful to Axel Bräunlich, Andreas J. Helbig, Dorit Liebers, Thomas Noah and Jörg Ratayczak for providing data and to Timur Iskakov, Tonya Grishina, Olga Koshkina and Gennadii Sidorin for their substantial logistical help. Surveys in 1999, 2000, 2002 and 2004 were funded by the ASA Program (administered by InWEnt), Naturschutzbund Deutschland (NABU) and the Royal Society for the Protection of Birds (RSPB). Surveys for Sociable Lapwing and Black-winged Pratincole were part-funded by the UK government’s Darwin Initiative and the Dutch ‘Van der Hucht De Beukelaar Stichting’.