ZOBODAT - www.zobodat.at Zoologisch-Botanische Datenbank/Zoological-Botanical Database Digitale Literatur/Digital Literature Zeitschrift/Journal: Libellula Jahr/Year: 2011 Band/Volume: 30 Autor(en)/Author(s): Schröter Asmus Artikel/Article: A mass migration of Aeshna affinis in southern Kyrgyzstan: attempt to provide a spatial and temporal reconstruction (Odonata: Aeshnidae) 203-233 ©Ges. deutschspr. Odonatologen e.V.; download www.libellula.org/libellula/ und www.zobodat.at Mass migration of Aeshna affinis in Kyrgyzstan 20. Dezember 2011203 A mass migration of Aeshna affinis in southern Kyrgyzstan: attempt to provide a spatial and temporal reconstruction (Odonata: Aeshnidae) Asmus Schröter Rasenweg 10, D-37130 Gleichen, <[email protected]> Abstract A mass migration of Aeshna affinis is reported for the first time. The phenomenon with preceding mass emergence took place in June 2009 in the Jalalabad province in southern Kyrgyzstan. The genesis of the mass migration is summed up, reconstructed and com- pared with common hypotheses and literature. With reference to the ecology of A. affinis in Europe, the prevailing ecological and climatic conditions are discussed. Zusammenfassung Eine Massenwanderung von Aeshna affinis im südlichen Kirgisistan: Versuch einer zeitli- chen und räumlichen Rekonstruktion (Odonata: Aeshnidae) – Im Juni 2009 wurde in der Provinz Jalalabad im südlichen Kirgisistan ein Massenschlupf von Aeshna affinis mit an- schließender Massenmigration beobachtet. Neben der räumlichen und zeitlichen Rekon- struktion des Szenarios werden die wichtigsten potenziell zugrunde liegenden ökologi- schen, klimatischen und physiologischen Kausalzusammenhänge diskutiert sowie die aus Europa bekannten Fakten zur Ökologie von A. affinis jenen in Kirgisistan gegenüberge- stellt. Introduction Migration of dragonflies is one of the most interesting and intriguing phenom- ena in odonatology, and the number of publications dealing with this subject runs into hundreds. A comprehensive review of worldwide published data was presented by Corbet (1999). There are various reasons for dragonflies to mi- grate. Some species are apparently obligate wanderers and long distance migraAnax- ephippigertion seems to be a crucial factor to circumvent unfavourable living conditions, such as seasonal droughts, as is demonstrated in an exemplary fashion by (Peters 1987; Corbet 1999: 412). Other speciesLibellula 30with (3/4) a 2011:highly 203-232 spe- ©Ges. deutschspr. Odonatologen e.V.; download www.libellula.org/libellula/ und www.zobodat.at 204 Asmus Schröter Sympetrumcialised life arenicolorcycle undertake an obligatory seasonal vertical migration to spend their pre-reproductive period in aestivation refuges, such as the Central Asian Anax junius (Borisov 2006b; Schröter 2010). Some species even ex- hibit birdlike autumnal southward migrations to avoid seasonal cold weather, as in , which was found accompanying mixed flocks of migrating birds heading south (Bagg 1957, 1958). Other species are facultative wanderers, mi- grating irregularly only under certain conditions triggered by climate and popu- lation dynamics, Aeshna mixta with a variationSympetrum in thestriolatum behaviour of different populations of the same species living under different ecological conditions. For instance, in Algeria and exhibit a vertical migration up the mountains to spend their pre-reproductive period in upland refuges with a favourableAnax microclimate parthenope (SamraouiSympetrum et al. 1998), fonscolombii whereas in temperate latitudes these species do not have any reason for an according migration. The same ap- plies to and in the Kazakh western Tian Shan, where both are supposed to undertake autumnal migrations south- wards (Borisov 2009), but according to current knowledge do not do so in the Central or Southern European part of their distribution. A trigger for many species to undertake spatial displacement is preceding mass emergence with subsequent high population densities (Fraenkel 1932; Dumont Libellula& Hinnekint quadrimaculata 1973; Corbet 1999). Such mass migrations have al- ways fascinated people and reports of huge swarms of migrating dragonflies, often of L. quadrimaculata, which might comprise billions of individu- als (Fraenkel 1932), date back to the 19th Century (Richter 1863; Corne- lius 1862). Some species like with a huge distribution area exhibit at more or less regular intervals mass abundances with subsequent swarm migration (Dumont & Hinnekint 1973; Haritonov & Popova 2011). On the other hand, species with different population Somatochloradynamics and arcticaless disposed to mass emergence never or only exceptionally reach an abundance level that might trigger mass migration. The inconspicuous , which in Europe is considered to be occurring locally and mainly in small numbers (WildermuthAeshna 2006), affinis may aggregate under optimal circumstances to swarms comprising thousands of individuals (Dijkstra & Koese 2001). This seems to apply also to , which in Europe is considered to be widespread but seldom abundant (Dijkstra 2006) and to date has never been found to migrate Aeshnain large affinis aggregations. has a large distribution area stretching from Western Europe over the Levant to Central Asia. In Europe, it is primarily found around the Mediter- ranean (Boudot et al. 2009). The following paper aims to outlineA. affnis an overall picture of the entire complex of mass migration on a generalA. affinis level and to reconstruct and summarize mass emergence and mass migration of on a local scale. A further objective is to extend our knowledge of in particular, providing new aspects of its ecology from the eastern edge of its distribution. Libellula 30 (3/4) 2011: 203-232 ©Ges. deutschspr. Odonatologen e.V.; download www.libellula.org/libellula/ und www.zobodat.at Mass migration of Aeshna affinis in Kyrgyzstan 205 Study region The Republic of Kyrgyzstan is the second smallest successor state of the five former Central Asian Soviet republics and shares borders with China, Tadzhiki- stan, Uzbekistan2 and Kazakhstan. It is landlocked and covers an area of roughly 200,000 km . Kyrgyzstan is a mountainous country, extending over the central and western part of the Tian Shan and the Trans-Alay range, both parts of the Hi- malayan orogenic belt. Dominated by high mountain ranges, almost 50 % of the national territory is situated at an altitude above 3,000 m and 90 % greater than 1,500 m above sea level (a.s.l.) (Maydell 1983: 154). The country’s geographical position between the glaciated peaks of the central Tian Shan and the adjacent desert region of the Turan Depression, however, offers an amazing variety of dif- ferent habitats, landscapes and climate types on a small scale. Арсланбоб; Жалалабат областы The studied area was situated in southern Kyrgyzstan close to the Usbek bor- der, near the town of ArslanbobБаубаш-Ата ( / Jalalabad province; 41°20’13.94’’N, 72°55’42.56’’E) in the walnut-fruit forest area at the foothills of the Baubash Ata ( ) mountain range. This mountain mas- sif is up to 4,427 m a.s.l. and covers approximately 30 km of the northwestern part of the Fergana ridge. Walnut-fruit forest is restricted to altitudes roughly between 1,000Juglans and 2,000regia m a.s.l., andAcer about turkestanicum 80 % is concentrated between 1,400 and 1,800 m a.s.l. (Kolov 1998;Malus Gan sieversii & VenglovskiPyrus 1997). korshinskyi The major tree speciesPrunus sogdianaare walnut Berberis, maple integerrima and several wild forms of fruit-bearing trees like apple , pear , plum and barberry . This forest represents the most extensive walnut forest stands worldwide and is characterized by remarkably high levels of genetic, species, and ecosystem biodiversity (Krassilov 1995; Hemery & Popov 1998). It is of major econom- ic importance for the local population (Borchardt et al. 2010; Schickhoff & Schmidt 2004). Due to increasing pressure of exploitation by a rapidly growing population and uncontrolled change to pasture, this unique ecosystem is severe- ly threatened (Kolov 1998; Gottschling et al. 2005; Borchardt et al. 2010; AS un publ.). The potential area that initially was covered by walnut-fruit forest is hard to reconstruct, as this forest has experienced a long period of human ex- ploitation. While the forest cover once may have reached the order of more than 350,000 ha, at present only 25,000-30,000 ha of dense walnut-fruit forest stands have remained (Scheuber et al. 2000; Gottschling 2005). Walnut-fruit forest is of high significance for Kyrgyzstan, which is one of the less wooded Asian countries with an entire forest cover of less than 4 % of the terri- tory (FAO 1990). The occurrence of dense deciduous forest is based on a specific regional climate, which deviates considerably from the arid and very continental macroclimate of southern Kyrgyzstan. While the adjacent desert lowland of the Fergana valley receives only a mean annual precipitation of 170-200 mm, the Libellula 30 (3/4) 2011: 203-232 ©Ges. deutschspr. Odonatologen e.V.; download www.libellula.org/libellula/ und www.zobodat.at 206 Asmus Schröter study region shows a considerably higher rate of precipitation, locally reaching at least 1,000 mm on an annual average (Franz 1973). According to Franz (1973) this is the highest precipitation rate in Kyrgyzstan. Precipitation reaches a peak from spring to early summer, a drought from mid- to late summer and a second peak in autumn (Fig. 7). The summers are usually hot with a high evaporation rate (Ponomarenko & Kenzhekaraev 1992).