Discovering the Migration and Non-Breeding Areas of Sand Martins and House Martins Breeding in the Pannonian Basin (Central-Eastern Europe)
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Journal of Avian Biology 48: 114–122, 2017 doi: 10.1111/jav.01339 © 2016 The Authors. This is an Online Open article Guest Editor: Anders Hedenström. Editor-in-Chief: Jan-Åke Nilsson. Accepted 15 November 2016 Discovering the migration and non-breeding areas of sand martins and house martins breeding in the Pannonian basin (central-eastern Europe) Tibor Szép, Felix Liechti, Károly Nagy, Zsolt Nagy and Steffen Hahn T. Szép, Inst. of Environmental Science, Univ. of Nyíregyháza, Nyíregyháza, Hungary. – F. Liechti ([email protected]) and S. Hahn, Dept of Bird Migration, Swiss Ornithological Inst., Sempach, Switzerland. – K. Nagy and Z. Nagy, MME/BirdLife, Budapest, Hungary. The central-eastern European populations of sand martin and house martin have declined in the last decades. The driv- ers for this decline cannot be identified as long as the whereabouts of these long distance migrants remain unknown outside the breeding season. Ringing recoveries of sand martins from central-eastern Europe are widely scattered in the Mediterranean basin and in Africa, suggesting various migration routes and a broad non-breeding range. The European populations of house martins are assumed to be longitudinally separated across their non-breeding range and thus narrow population-specific non-breeding areas are expected. By using geolocators, we identified for the first time, the migration routes and non-breeding areas of sand martins (n 4) and house martins (n 5) breeding in central-eastern Europe. In autumn, the Carpathian Bend and northern parts of the Balkan Peninsula serve as important pre-migration areas for both species. All individuals crossed the Mediterranean Sea from Greece to Libya. Sand martins spent the non-breeding season in northern Cameroon and the Lake Chad Basin, within less than a 700 km radius, while house martins were widely scattered in three distinct regions in central, eastern, and southern Africa. Thus, for both species, the expected strength of migratory connectivity could not be confirmed. House martins, but not sand martins, migrated about twice as fast in spring compared to autumn. The spring migra- tion started with a net average speed of 400 km d–1 for sand martins, and 800 km d–1 for house martins. However, both species used several stopover sites for 0.5–4 d and were stationary for nearly half of their spring migration. Arrival at breeding grounds was mainly related to departure from the last sub-Saharan non-breeding site rather than distance, route, or stopovers. We assume a strong carry-over effect on timing in spring. Various populations of long distance migratory birds in the significantly since 1999, whereas only 8% show positive western Palearctic have declined in recent decades (Sander- trends (Szép et al. 2012). The information deficiency in rela- son et al. 2006). Candidate factors are climate change (Both tion to the migration and non-breeding areas of these popu- et al. 2006), changes of habitats in breeding (Donald et al. lations are immense, especially as they often play key roles on 2001), migration, and non-breeding areas (Zwarts et al. the dynamics of the entire European populations (BirdLife 2009, Maggini and Bairlein 2011). To identify carry-over 2004). The sand martin Riparia riparia and house martin effects and seasonal interactions on population development Delichon urbicum are typical examples: their populations (Harrison et al. 2011) we need comprehensive knowledge suffered from strong declines with mean annual population about the whereabouts of individuals during the entire growth rates of –2.7% in sand martins (during 1986–2014, annual cycle. In contrast to detailed information available Szép unpubl.) and –4.7% in house martins (1999–2014, for breeding periods, we are still lacking information for Szép et al. 2012). Information on their distribution during migration and non-breeding periods (Vickery et al. 2014), the non-breeding period is almost entirely lacking. especially for long distance passerine species. The sand martins breeding in eastern Hungary were In the Pannonian basin (central-eastern Europe), 58% out found among the first where adverse climate conditions in of 26 common long distance migrant species have declined potential African non-breeding areas (Sahel) could be cor- related with the decreasing annual survival rates (Szép 1995). This is an open access article under the terms of the Creative Despite the huge effort on ringing with almost 140 000 indi- Commons Attribution License, which permits use, distribution viduals in eastern Hungary during more than 30 yr, there and reproduction in any medium, provided the original work is is no recovery in Africa for this breeding population. For properly cited. other Hungarian and the neighbouring Czech and Slovakian 114 populations, there are only eight recoveries from the African size 100 pairs). Average body mass of the geolocator-har- continent, Lake Chad (2), Morocco, east of Tunisia (4), DR nessed birds at deployment was 13.4 g (SD 0.80, n 80); Congo and two nearby recoveries from Israel and Lebanon thus geolocators mass was 4.5% of body mass. in spring (Heneberg 2008, Szép 2009). Thus, sand martins We recaptured five sand martins in May–June of 2013 are assumed to migrate on a broad front (Turner and Rose (two females and one male at Szabolcs and two females 1989), and should be widely distributed in sub-Saharan at Gávavencsellő), and received geolocator data from four Africa, eastern and southern Africa (Walther et al. 2010). birds (one geolocator failed). Additionally, another female The house martin is one of the ten most common Palae- with a geolocator was identified at Szabolcs using a digital arctic African migrants (Hahn et al 2009) but spatial infor- camera, but was not recaptured. All recaptured birds were mation during the non-breeding season is very scant (Hill active breeders. The return rate of geolocator-harnessed birds 1997). For birds breeding in Germany there are just six varied between Szabolcs (5.8%) and Gávavencsellő (18.2%), recoveries from the African non-breeding areas spanning but not significantly (Fisher’s exact test, p 0.19). Return the Central African Republic, Cameroon, DR Congo, and rates of geolocator-harnessed birds and controls (caught at Zambia (Bairlein et al. 2014). Moreover for the large popu- the same catching events in 2012) showed significant dif- lation in the UK, there is only a single recovery from Nigeria ference at Szabolcs (control: 17.8%, n 129, geolocators: (Hill 2002). House martins breeding in northern Europe 5.8%, n 69 birds, Fisher’s exact test, p 0.028), but not had been recovered in southern Africa (Hill 2002, Valkama at Gávavencsellő (control: 21.7%, n 46, geolocators: 2014), whereas the little available information for birds from 18.2%, n 11, Fisher’s exact test, p 1.0). The return rate central-eastern Europe points to migration routes across the of females was double that of males, but the difference was Balkan peninsula, southern Italy and north-western Libya not significant (female: 4/40, male: 2/40, Fisher’s exact test, during autumn, and north-western Algeria, Malta, and the p 0.67). Balkans during spring (Cepák 2008, Králl and Karcza 2009). House martins were equipped with geolocators at Albeit small, this tantalising information raises the sugges- Nagyhalász-Homoktanya (48.076°N, 21.752°E 21 males, tion that European house martins might be longitudinally 18 females and 1 adult of unknown sex) and at Tiszabercel separated in Africa with eastern populations overwintering (48.158°N, 21.643°E three males and seven females between in east Africa, central populations in Zambia, Zimbabwe 19 July and 3 August 2012). The mean body mass of geolo- and South Africa, and western populations distributed in the cator-harnessed birds was 17.1 g (SD 1.04, n 50), while region of the Bight of Benin (Hill 2002). the geolocator mass was 3.5% of adult body mass. The colony In this paper we investigate the migration and non-breed- at Nagyhalász-Homoktanya comprised 317 nests (41% with ing areas of sand martins and house martins breeding in the clutches), whereas at Tiszabercel the colony consisted of Pannonian basin using geolocators, and compare our results 43 nests (51% with clutches). with the ringing recoveries of the two species during the Five geolocator-harnessed birds were recaptured at non-breeding season. Finally, we also study the diurnal and the colony of Nagyhalász-Homoktanya (three males, two nocturnal use of cavities during the non-breeding season to females) in July of 2013. The return rate (12.5%) was lower explain the very low numbers of African recoveries especially than 38.9% return rate of control birds (n 18) (Fisher’s for house martins. exact test, p 0.035). At Tiszabercel neither geolocator nor control birds were recaptured. Methods Light-level data analysis Studied populations We calculated positions using the R-package GeoLight (Lis- ovski and Hahn 2012). However, we could not use light The sand martin population we studied breeds along the data from breeding ranges to calibrate sun elevation angles river Tisza in eastern Hungary and has been intensively because of the non-natural sunset and sunrise that the birds monitored since 1986 (Szép et al. 2003b). The house mar- experienced inside cavities where they nest. We therefore tin colonies we studied are situated in two villages along the used median sun elevation angle (–2.7°) for all individu- upper section of the river Tisza, where 40–280 birds have als of both species derived by the Hill–Ekstrom calibration been ringed annually since 2010. method (Lisovski and Hahn 2012) from long non-breeding stationary periods ( 50 d). This sun elevation angle was Deployment of geolocators very close to the one measured with the same geolocator type in another study (–2.8) that looked at more than 100 barn In 2012, we equipped adult breeders of both species with swallows (Liechti et al.