Bird Conservation International (2010) 20:186–199. ª BirdLife International, 2010 doi:10.1017/S0959270910000031 Wader, gull and tern population estimates for a key breeding and stopover site in Central Kazakhstan HOLGER SCHIELZETH, JOHANNES KAMP, GO¨ TZ EICHHORN, THOMAS HEINICKE, MAXIM A. KOSHKIN, LARS LACHMANN, ROBERT D. SHELDON and ALEXEJ V. KOSHKIN Summary Population size estimates of waders, gulls and terns passing through or breeding in Central Asia are very scarce, although highly important for global flyway population estimates as well as for targeting local conservation efforts. The Tengiz-Korgalzhyn region is one of the largest wetland complexes in Central Asia. We conducted surveys in this region between 1999 and 2008 and present estimates of population size as well as information on phenology and age structure for 50 species of Charadriiformes. The Tengiz-Korgalzhyn wetlands are especially important for Red- necked Phalaropes Phalaropus lobatus and Ruffs Philomachus pugnax with, respectively, 41% and 13% of their flyway populations using the area during spring migration. The region is also an important post-breeding moulting site for Pied Avocets Recurvirostra avosetta and Black- tailed Godwits Limosa limosa used by, respectively, 5% and 4% of their flyway populations. Besides its key importance as a migratory stopover site, the study area is a key breeding site for the Critically Endangered Sociable Lapwing Vanellus gregarius, the Near Threatened Black- winged Pratincole Glareola nordmanni and for Pallas’s Gull Larus ichthyaetus with 16%, 6% and 5% of their world populations, respectively. We identified 29 individual sites that held more than 1% of the relevant flyway populations of at least one species of Charadriiformes. Including data on other species of waterbirds (mainly waterfowl), there were 93 sites that qualify for Important Bird Areas (IBA). About half of them are protected in a state nature reserve, while an additional 20% are recognised as IBAs. Nevertheless, 28 important sites are currently not recognised as IBAs nor are they protected by other conservation means. These sites require conservation attention. Introduction 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. 2005, Davidson and Stroud 2006, Delany et al. 2009). 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. 2004, Delany et al. 2009). 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. 1985, Eichhorn 2001, Koshkin Wader and larid populations in Central Kazakhstan 187 and Koshkina 2003, Gavrilov and Gavrilov 2005, Schielzeth et al. 2008), 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. 2006). 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 1999, 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, 2 covering almost 150,000 km , equivalent to 5.5% of the country area (Sklyarenko et al. 2008). 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. 2008) 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 Study area The study region encompasses an area of about 180 3 150 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 2,589 km , Sklyarenko et al. 2008) 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 2 been identified in the Tengiz-Korgalzhyn area, totalling 837 km (Sklyarenko et al. 2008, 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 Table 1. Important Bird Areas (IBA) in the Tengiz-Korgalzhyn region. Official name IBA No Area Conservation status Criteria Korgalzhyn State Nature Reserve KZ051 258,963 ha zapovednik A1,A3,A4i, A4iii Amangeldy KZ052 5,536 ha unprotected A1,A3,A4i, A4iii Zhumay-Mayshukyr Lake System KZ053 12,490 ha largely unprotected A1,A3,A4i, A4iii (but small part is zapovednik) Vicinity of Korgalzhyn village KZ054 12,280 ha unprotected A1,A3,A4i, A4iii Uyalyshalkar Lake System KZ055 20,360 ha unprotected A1,A3,A4i, A4iii Kumdykol-Zharlykol Lake System KZ056 20,350 ha unprotected A1,A3,A4i, A4iii Aktubek KZ057 6,157 ha unprotected A1,A3,A4i Tuzashchy and Karasor Lake KZ058 8,582 ha unprotected A1,A4i, A4iii H. Schielzeth et al. 188 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. Survey methods Most of the data analysed here were collected together with data on other waterbird species analysed by Schielzeth et al. (2008), 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. 2009). 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. (2008), 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 Xn Njk 5 cijk i51 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 Xn Nk 5 aik i51 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.