Oikos 118: 624Á626, 2009 doi: 10.1111/j.1600-0706.2009.17309.x, # 2009 The Authors. Journal compilation # 2009 Oikos Subject Editor: Hamish McCallum. Accepted 3 November 2008

The natural link between and 2.1 billion on migration Á

Steffen Hahn, Silke Bauer and Felix Liechti

S. Hahn ([email protected]), S. Bauer and F. Liechti, Swiss Ornithological Inst., Luzernerstrasse 6, CHÁ6203 Sempach, Switzerland. SB also at: Dept of PlantÁAnimalÁInteractions, Centre for Limnology, Inst. of Ecology (NIOO-KNAW), PO Box 1299, NLÁ3600 BG Maarssen, the Netherlands.

The PalaearcticÁAfrican migration system comprises enormous numbers of birds travelling between Europe and Africa twice each year. Migratory birds may form strong links between the two continents given they can act as both transport vehicles for parasites and diseases as well as temporary consumers with increased food demand to fuel their flight. Knowing the number of migrating birds is crucial if such links are to be quantified. We estimate that today approximately 2.1 billion songbirds and near- birds migrate from Europe to Africa in autumn, 73% of which are accounted for by just 16 species. This number is only half the estimate from the 1950s in the only other assessment to date. The discrepancy is mainly caused by the limited information on population sizes in the past. Our estimated number of migrants is highly dependent on the accuracy of the underlying estimates of breeding population sizes, as well as breeding parameters in species with relatively high reproductive output. The updated figures quantify and emphasize the strong natural connection between Africa and Europe, which has important implications for manifold research topics including those related to climate change, human health and biological conservation.

‘‘Let us now toss a few figures into the air.’’ With these between Europe and Africa in boreal autumn. Additionally, words Moreau (1972, p. 45) introduced his attempt to we reconsidered Moreau’s calculations to identify the cause estimate the number of birds involved in the world’s biggest of potential differences Á be they methodological or due to migration system, the PalaearcticÁAfrican flyway actual changes in populations sizes. (Newton 2008). Migratory birds connect the two con- tinents and their different biomes twice each year. Through the transportation of disease (Hubalek 2004) and disease Methods vectors (Comstedt et al. 2006), parasites (Waldenstrom et al. 2002), seeds (Sanchez et al. 2006), and the harvesting We focused on the autumn migration of birds from their of considerable amounts of food while preparing for flight European breeding grounds, within the geographical (Alerstam and Lindstro¨m 1990, Fransson et al. 2008) they borders of Europe including Turkey and European Russia seasonally alter the composition of local communities at (to approx. 608E), to their sub-Saharan African wintering their sites of origin, as well as stop-over and destination quarters. Bird populations were assumed to include sites. Estimating the number of birds migrating between breeders, their offspring and non-breeding adults. We Europe and Africa is of utmost importance when we strive considered 55 passerine and 13 near-passerine species, i.e. to quantify such links. Eurasian wryneck Jynx torquilla, European roller Coracias However, to date, the only estimate of how many birds garrulus, Eurasian hoopoe Upupa epops, -eaters Merops migrate between the two continents stems from Moreau’s sp., swifts Apus sp., Tachymarptis melba, nightjars Capri- pioneering work (Moreau 1972) that deduced the impress- mulgus sp., Cuculus canorus, European ive number of 5 billion migrating landbirds, dominated turtle dove Streptopelia turtur and common quail Coturnix by 4.3 billion . Although this figure has been coturnix, all migrating to sub-Saharan regions (Supple- heavily used in subsequent works, it has not been revisited mentary material Appendix 1, Table A1). We used since its publication more than 30 years ago. published estimates of current population sizes of birds We used current data on breeding population sizes, breeding within the above mentioned region (BirdLife reproductive success, proportions of young and non- International 2004). We determined the proportion of breeders of species from Europe including Turkey and long-distance migrants within each population using European Russia to establish a current estimate of the information derived from Glutz von Blotzheim and Bauer number of passerine and near-passerine birds migrating (1987) and Cramp (1998). In five species, bluethroat

624 Luscinia svecica, common chiffchaff Phylloscopus collybita, Results Sylvia atricapilla, Eurasian hoopoe and common quail, considerable parts of the European breed- Based on the size of breeding populations of European ing population undertake partial migrations with several species (BirdLife International 2004), we estimated that in sub-populations wintering north of the . For these total, between 1.52 and 2.91 (average 2.1) billion passerine species we assumed complete residency in Mediterranean and near-passerine birds cross the Sahara each autumn to populations and/or a mixed migration strategy, with 50% spend the non-breeding season in sub-Saharan Africa. of individuals in populations along a corridor throughout Passerines account for 95% of all individuals. Moreover, central Europe over-winter north of the Sahara. The 73% of these long-distance migrants belong to 16 species resulting numbers of birds, which don’t migrate to (Fig. 1) of which the willow warbler Phylloscopus trochilus is sub-Saharan Africa, have been subtracted from their the most numerous (15.8%), followed by tree pipit Anthus European migrant population size (Supplementary Mate- trivialis (7.3%), common chiffchaff and barn swallow rial Appendix 1, Table A2). Hirundo rustica (both 6.5%). Population composition The number of first-year birds on migration was derived varied between species according to their mean breeding from data of mean annual breeding success (no. of success. On average, 47% of migrants were adults (minÁ fledglings per ), the average number of breeding max: 30Á63%), 46% juveniles (27Á66%) and 7% non- attempts per season and the estimated survival from breeders (4Á10%, Fig. 1). fledging until departure. Data on reproduction were derived The accuracy of these estimates is principally reliant from Glutz von Blotzheim and Bauer (1987) and Cramp upon published data of the species’ breeding population (1998); some missing values were substituted with averages sizes; varying this parameter for all species by 10% would, from the closest relatives. Survival estimates for the post- of course, also change the estimated total number of fledging period were lacking for most species. Therefore, we migrants by 10%. Similarly, variations in clutch size, used a median survival rate of 0.6 for all species by taking breeding success and fledging survival entail changes of the average fledgling survival of the six passerine species for 4.9% each (at species level: minimum 2.71%, maximum: which data were available (Naef-Daenzer et al. 2001, 6.58%). Less important were the proportions of non- Kershner et al. 2004, Gru¨ebler 2007, Wells et al. 2007). breeders and resident birds in the total population, which Finally, the proportion of non-breeders within a population change the overall estimate by only 0.9% and 0.6%, was estimated to be 15%, the median of seven passerines respectively (species: minÁmax: 0.45Á0.95%). Finally, (Newton 1998). assuming that a long-distance migration strategy is em- Because parameter estimates might be subject to in- ployed by the entire population for all species would accuracy, we determined the sensitivity of the output increase the total number of migrants by 7.9%. (number of migrating birds) to variation in each parameter. Therefore, we subsequently changed all parameters by 910%, re-calculated the output and, finally related the Discussion changes in the focal parameter to the resulting changes in the output value (Hamby 1994). Moreau (1972) based his calculations on population-size All population-relevant averages are geometric means. estimates of Finnish birds from the 1950s (Merikallio

willow warbler tree pipit common chiffchaff* barn swallow common house martin wood warbler Eurasian blackcap* northern wheatear western yellow wagtail breeding adults greater short-toed lark juveniles non-breeding adults 0 100 200 300 400 No. birds (× 106)

Figure 1. The 16 most abundant long-distance migratory species crossing the Mediterranean Sea and the Sahara desert, representing 73% of all European passerines and near-passerines during autumn migration. Bar length gives the geometric mean number of breeding adults, their juveniles and the non-breeding adults per species; the error bars indicate minimum and maximum numbers. Asterisks mark species with partially migratory populations.

625 1958), and estimated that 4.3 billion passerines and 200 E. (ed.), : physiology and ecophysiology. million near-passerines migrate to Africa in autumn. Our Springer, pp. 331Á351. calculations result in numbers that are only half these earlier BirdLife International 2004. Birds in Europe: population esti- estimates. For almost all of Moreau’s 16 most abundant mates, trends and conservation status. Á BirdLife International. species, their current population size appears to be Comstedt, P. et al. 2006. Migratory passerine birds as reservoirs of moderately to drastically lower than in his estimates lyme borreliosis in Europe. Á Emerging Infectious Dis. 12: 1087Á1095. (between 10 and 84% of the former numbers, the only Cramp, S. 1998. The complete birds of the western Palearctic. exception being the European pied flycatcher Ficedual Á Oxford Univ. Press. hypoleuca with a 2.5-fold higher number). This does not, Fransson, T. et al. 2008. When and where to fuel before crossing however, imply that long-distance migrants have necessarily the Sahara desert-extended stopover and migratory fuelling in decreased to only half their population sizes in the 1950s. first-year garden warblers Sylvia borin. Á J. Avian Biol. 39: Only two out of 16 species experienced great decreases in 133Á138. numbers, with all others remaining stable or showing slight Glutz von Blotzheim, U. N. and Bauer, K. M. 1987. Handbuch decreases over the last 30 years (BirdLife International der Vo¨gel Mitteleuropas. Á AULA-Verlag. 2004). If we re-calculate population numbers for the 1970s Gru¨ebler, M. U. 2007. Time constraints of breeding twice: on the based on current estimates and assuming they have under- fitness relevance of timing of reproduction and post-fledging gone a large decrease (defined as a decline in population size in the barn swallow (Hirundo rustica). by at least 20% in at least 66% of the population, Tucker PhD thesis. Á Univ. of Zurich. and Heath 1994), we still arrive at population sizes much Hamby, D. M. 1994. A review of techniques for parameter lower than the Moreau estimate for all species except the sensitivity analysis of environmental models. Á Environ. common house martin Delichon urbicum and European Monit. Assess. 32: 135Á154. pied flycatcher. This discrepancy would be even greater if Hubalek, Z. 2004. An annotated checklist of pathogenic micro- organisms associated with migratory birds. Á J. Wildlife Dis. Moreau had considered the non-breeders as we did in our 40: 639Á659. calculations. On the other hand, we have limited our Kershner, E. L. et al. 2004. Postfledging movements and survival analyses to breeding populations of the western and central of juvenile eastern meadowlarks (Sturnella magna) in Illinois. Palaearctic, i.e. east to 608E, but some birds even further Á Auk 121: 1146Á1154. east also migrate to Africa. However, because the sizes of Merikallio, E. 1958. Finnish birds, their distribution and these easterly breeding populations are poorly known, we numbers. Á Fauna Fenn. 5: 1Á180. have omitted them from our calculations. Moreau, R. E. 1972. The PalaearcticÁAfrican bird migration Nonetheless, we arrive at the impressive number of systems. Á Academic Press. 2 billion passerines and near-passerine birds migrating from Naef-Daenzer, B. et al. 2001. Differential post-fledging survival of the European continent to sub-Saharan Africa in autumn great and coal tits in relation to their condition and fledging each year. This constitutes more than one quarter of all date. Á J. Anim. Ecol. 70: 730Á738. European breeding birds. Newton, I. 1998. Population limitation in birds. Á Academic The strong natural link between Europe and Africa Press. evidenced by the huge number of migrating birds Newton, I. 2008. The migration ecology of birds. Á Academic Press. emphasizes the importance of distant habitats for the Sanchez, M. I. et al. 2006. Internal transport of seeds by migratory survival of local populations. Quantification of this waders in the Odiel marshes, south-west Spain: consequences connectivity is a prerequisite for the global view required for long-distance dispersal. Á J. Avian Biol. 37: 201Á206. to understand and predict future changes in our biological Tucker, G. M. and Heath, M. F. 1994. Birds in Europe: their environment. conservation status. Á BirdLife International. Waldenstrom, J. et al. 2002. Cross-species infection of blood Acknowledgements Á We are grateful to B. Bruderer and O. parasites between resident and migratory songbirds in Africa. Meinen for first ideas on the subject. Additionally, we want to Á Mol. Ecol. 11: 1545Á1554. thank B. Hoye, L. Jenni and M. Klaassen for stimulating Wells, K. M. S. et al. 2007. Survival of postfledging grassland birds discussion and comments on the manuscript. This is publication in Missouri. Á Condor 109: 781Á794. 4423 of the Netherlands Institute of Ecology (NIOO-KNAW).

References Supplementary material (available online as Appendix Alerstam, T. and Lindstro¨m, A. 1990. Optimal bird migration: the O17309 at /). Appendix relative importance of time, energy, and safety. Á In: Gwinner, 1: Table A1 and Table A2.

626 No. migrants_ No. max 1.02E+07 1.07E+05 2.69E+07 2.96E+07 1.92E+07 7.61E+06 1.30E+07 1.91E+08 5.44E+07 5.65E+05 5.57E+07 3.16E+06 3.48E+05 4.84E+05 1.88E+07 3.40E+07 1.18E+08 5.93E+07 3.98E+05 1.07E+07 9.57E+07 2.37E+05 3.19E+07 1.40E+05 8.52E+04 2.38E+07 1.05E+07 2.81E+06 2.03E+08 7.71E+06 No. migrants_ No. min 5.30E+06 6.41E+04 1.27E+07 1.76E+07 1.04E+07 4.01E+06 4.35E+06 1.23E+08 2.21E+07 1.38E+05 2.91E+07 1.49E+06 6.64E+04 2.33E+05 1.12E+07 1.66E+07 4.87E+07 1.93E+07 1.33E+05 6.27E+06 5.74E+07 6.70E+04 1.57E+07 5.29E+04 4.07E+04 1.17E+07 3.51E+06 6.54E+05 9.04E+07 3.44E+06 BP_max 2.90E+06 2.00E+04 6.80E+06 7.40E+06 5.00E+06 1.90E+06 3.00E+06 4.20E+07 1.70E+07 1.60E+05 1.40E+07 1.00E+06 1.10E+05 1.10E+05 4.70E+06 8.60E+06 2.40E+07 1.60E+07 9.60E+04 2.40E+06 2.00E+07 5.30E+04 7.10E+06 3.70E+04 2.30E+04 6.70E+06 3.00E+06 4.30E+05 3.60E+07 1.30E+06 BP_min 1.50E+06 1.20E+04 3.20E+06 4.40E+06 2.70E+06 1.00E+06 1.00E+06 2.70E+07 6.90E+06 3.90E+04 7.30E+06 4.70E+05 2.10E+04 5.30E+04 2.80E+06 4.20E+06 9.90E+06 5.20E+06 3.20E+04 1.40E+06 1.20E+07 1.50E+04 3.50E+06 1.40E+04 1.10E+04 3.30E+06 1.00E+06 1.00E+05 1.60E+07 5.80E+05 p No. offspring 2.05 5.07 2.77 2.84 2.57 2.84 3.41 3.73 1.50 2.05 2.80 1.44 1.44 3.50 4.49 2.76 4.37 2.35 3.08 3.63 4.14 3.61 3.65 2.46 2.34 2.09 2.02 7.07 5.58 6.05 f g h b i i i BS 0.44 0.68 0.54 0.54 0.55 0.68 0.62 0.54 0.64 0.41 0.40 0.48 0.48 0.92 0.44 0.30 0.71 0.51 0.44 0.61 0.70 0.66 0.76 0.62 0.62 0.62 0.47 0.74 0.82 0.60 b c c No. No. broods 1.00 1.50 1.00 1.00 1.20 1.00 1.00 1.50 1.00 2.00 2.00 1.50 1.50 1.00 1.00 1.00 1.50 1.00 2.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 2.20 1.50 1.20 a CS 4.70 5.00 5.13 5.25 3.90 4.18 5.50 4.61 2.35 2.50 3.50 2.00 2.00 3.80 10.20 9.20 4.10 4.60 3.50 5.93 5.92 5.50 4.80 4.00 3.80 3.40 4.30 4.32 4.54 8.40 Order 1 1 1 1 1 1 1 1 2 2 1 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 2 Common name warbler reed great aquatic warbler marsh warbler sedge warbler reed-warbler Eurasian tawny pipit pipit red-throated pipit tree common swift pallid swift short-toed lark greater nightjar Eurasian nightjar red-necked roller European common quail common cuckoo common house martin ortolan bunting rufous-tailed scrub robin flycatcher collared pied flycatcher European flycatcher semicollared icterine warbler warbler Upcher’s warbler -tree warbler eastern olivaceous melodious warbler red-rumped swallow barn swallow wryneckEurasian Scientific name arundinaceus Acrocephalus A. paludicola A. palustris A. schoenobaenus A. scirpaceus A. campestris A. cervinus A. trivialis apus Apus A. pallidus brachydactyla Calandrella europaeus Caprimulgus C. ruficollis garrulus Coracias Coturnix coturnix canorus Cuculus urbica Delichon hortulana Emberiza galactotes Erythropygia albicollis hypoleuca F. semitorquata F. icterina Hippolais H. languida H. olivetorum H. pallida H. polyglotta daurica Hirundo H. rustica torquilla Jynx Table A1. Breeding parameters, breeding population size and the resulting number of individuals of European passerine and near-passerine species migrating to sub-Saharan Africa in autumn. autumn. in Africa sub-Saharan to 1 Appendix migrating species near-passerine and no. passerine success, European breeding of – BS individuals season, of per number numbers broods of resulting the number and resulting – size the broods are population no. nest), breeding per migrants_min/max of parameters, no. (no. Breeding and size A1. clutch (2004), Table average – CS International non-passerine); 2: BirdLife to passerine, (1: according order Europe systematic in – pairs order are: breeding columns The are BP_min/max season. and pair per offspring of number – offspring (1998), if not stated otherwise (1987) and Cramp and Bauer (see: superscripts). Blotzheim von Glutz calculated from averages parameters are of individuals on autumn migration. Breeding No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30

2 5.56E+07 6.32E+06 5.40E+05 4.48E+06 1.80E+07 3.05E+06 1.08E+07 3.12E+07 6.77E+07 4.25E+07 4.82E+06 4.82E+04 1.31E+06 5.92E+07 1.26E+08 8.05E+05 1.81E+07 3.13E+07 7.94E+07 2.78E+07 1.08E+08 1.35E+07 1.74E+08 8.23E+07 4.42E+08 5.15E+07 4.01E+07 2.44E+07 7.74E+07 1.12E+08 1.54E+07 1.09E+08 2.98E+07 1.52E+06 4.44E+06 2.23E+06 1.09E+06 4.48E+06 2.69E+07 2.61E+06 1.89E+05 1.79E+06 7.42E+06 2.02E+06 4.11E+06 1.67E+07 2.37E+07 2.46E+07 2.31E+06 1.49E+04 4.11E+05 3.34E+07 7.99E+07 4.02E+05 7.69E+06 1.04E+07 2.81E+07 1.33E+07 4.57E+07 5.42E+06 1.07E+08 5.23E+07 2.48E+08 2.93E+07 2.16E+07 1.18E+07 4.79E+07 6.16E+07 6.75E+06 6.13E+07 1.83E+07 5.37E+05 2.04E+06 7.30E+05 4.61E+05 2.30E+06 1.30E+07 1.50E+06 1.00E+05 1.20E+06 4.60E+06 8.00E+05 2.20E+06 6.90E+06 1.20E+07 7.80E+06 1.00E+06 1.00E+04 3.20E+05 1.40E+07 2.20E+07 1.80E+05 3.30E+06 6.30E+06 1.30E+07 7.10E+06 1.60E+07 3.50E+06 6.00E+07 2.20E+07 1.00E+08 9.50E+06 1.00E+07 7.20E+06 4.90E+07 3.10E+07 3.20E+06 2.50E+07 7.80E+06 4.80E+05 1.00E+06 6.10E+05 3.30E+05 1.70E+06 6.30E+06 6.20E+05 3.50E+04 4.80E+05 1.90E+06 5.30E+05 8.40E+05 3.70E+06 4.20E+06 4.50E+06 4.80E+05 3.10E+03 1.00E+05 7.90E+06 1.40E+07 9.00E+04 1.40E+06 2.10E+06 4.60E+06 3.40E+06 6.80E+06 1.40E+06 3.00E+07 1.40E+07 5.60E+07 5.40E+06 5.40E+06 3.50E+06 2.50E+07 1.70E+07 1.40E+06 1.40E+07 4.80E+06 1.70E+05 4.60E+05 2.00E+05 1.40E+05 8.90E+05 3.30 3.19 5.17 2.39 2.68 2.51 4.32 3.70 5.57 5.34 4.20 4.20 3.02 3.22 5.68 3.62 5.33 4.44 6.35 2.70 7.37 2.61 4.77 2.40 3.54 5.20 2.85 1.81 2.58 2.21 4.20 3.46 2.53 1.43 3.57 2.25 1.65 3.68 j j k l d m m m n e e 0.65 0.55 0.55 0.46 0.39 0.42 0.40 0.77 0.77 0.58 0.70 0.70 0.67 0.59 0.66 0.67 0.67 0.62 0.72 0.71 0.75 0.49 0.51 0.41 0.56 0.64 0.48 0.38 0.51 0.49 0.50 0.57 0.52 0.34 0.76 0.50 0.66 0.53 d e e 1.00 1.00 2.00 1.00 1.40 1.30 2.00 1.00 1.50 1.50 1.00 1.00 1.00 1.00 2.00 1.20 1.50 1.35 1.47 1.00 1.60 1.00 1.70 1.00 1.00 1.70 1.00 2.50 1.10 1.00 2.00 1.30 1.00 1.00 1.00 1.00 1.00 1.00 5.07 5.80 4.70 5.20 4.90 4.60 5.40 4.80 4.82 6.19 6.00 6.00 4.50 5.45 4.30 4.50 5.30 5.30 6.00 3.80 6.15 5.30 5.50 5.85 6.32 4.78 5.93 1.90 4.60 4.50 4.20 4.67 4.86 4.20 4.70 4.50 2.50 7.00 1 1 1 1 1 1 1 1 1 1 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1 1 1 1 1 1 1 2 2 red-backed shrike red-backed shrike lesser grey masked shrike woodchat shrike warbler river warbler Savi’s common grasshopper warbler thrush nightingale common nightingale bluethroat bee-eater European blue-cheeked bee-eater rufous-tailed thrush rock wagtail yellow western spotted flycatcher wheatear Cyprus wheatear black-eared isabelline wheatear northern wheatear golden oriole Eurasian common redstart warbler Bonelli’s western common chiffchaff wood warbler warbler willow sand martin turtle dove European blackcap Eurasian warbler garden subalpine warbler common whitethroat orphean warbler warbler Rueppell’s alpine swift hoopoe Eurasian Lanius collurio L. minor L. nubicus L. senator Locustella fluviatilis L. luscinioides L. naevia luscinia Luscinia L. megarhynchos L. svecica apiaster Merops M. persicus saxatilis Monticola flava Motacilla striata Muscicapa cypriaca Oenanthe O. hispanica O. isabellina O. oenanthe oriolus Oriolus Phoenicurus phoenicurus bonelli Phylloscopus collybita P. sibilatrix P. trochilus P. Riparia riparia rubetra Saxicola turtur Streptopelia atricapilla Sylvia S. borin S. cantillans S. communis S. curruca S. hortensis S. nisoria S. rueppelli melba Tachymarptis epops Upupa 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68

3 - 41.6 2000 8000 7000 1000 14000 50000 20000 50000 10000 42000 710000 100000 400000 707000 BP_max 600 42.6 1000 4000 5000 3500 3000 10000 30000 20000 10000 24000 497000 150000 379050 BP_min Upupa epops Upupa

Eurasian hoopoe Eurasian 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Prop 59.0 50000 20000 20000 250000 300000 932000 150000 320000 500000 900000 900000 160000 BP_max 1400000 2000000 1500000 1600000 3500000 1500000 1000000 1050000 5000000 1000000 10000000 28892000 50.2 5000 20000 10000 60000 50000 80000 700000 100000 800000 200000 800000 850000 932000 500000 790000 270000 650000 600000 800000 BP_min 1000000 2000000 2500000 2000000 12562000 Sylvia atricapilla Sylvia Eurasian backcap backcap Eurasian

1.0 0.5 0.5 1.0 0.5 1.0 0.5 0.5 1.0 1.0 1.0 1.0 1.0 0.5 1.0 1.0 1.0 0.5 1.0 0.5 1.0 0.5 1.0 Prop 100 43.7 5000 60000 50000 250000 300000 750000 807000 800000 720000 100000 800000 300000 600000 600000 400000 BP_max 1000000 1000000 1600000 4000000 1600000 1000000 ) we set %TBP tentatively to 20% (del Hoyo et after al. ISO1994). abbreviated Countries are ) set we %TBP to tentatively 20% (del Hoyo 15000000 26207100 10 (Cramp 1998), i: mean (no. 23, 27), j: mean (no. 31, 34), k: mean (no. 35, 36), l: no. 38, m: mean (no. (no. mean m: 38, no. l: 36), 35, (no. mean k: 34), 31, (no. mean j: 27), 23, (no. mean i: 1998), (Cramp 31.2 2000 40000 20000 20000 50000 600000 100000 300000 200000 450000 800000 807000 500000 520000 300000 550000 980000 400000 600000 100000 BP_min 2400000 3000000 9364010 Coturnix coturnix Common chiffchaff Phylloscopus collybita Phylloscopus Perdix perdix perdix Perdix

1.0 0.5 0.5 1.0 0.5 1.0 0.5 0.5 1.0 1.0 1.0 1.0 1.0 0.5 1.0 1.0 1.0 0.5 1.0 0.5 1.0 0.5 1.0 Prop 7 5 75 30 0.4 350 150 600 800 4100 4600 3500 3000 12800 40000 11000 33895 BP_max 1 0 50 15 0.3 250 100 400 500 3100 3300 9000 9000 1500 1000 10000 14976 (Cramp 1998), g: 12, no. h: based on Bluethroat BP_min Luscinia svecica Luscinia

0.5 0.5 0.5 1.0 0.5 0.5 1.0 1.0 1.0 0.5 0.5 1.0 0.5 0.5 1.0 Prop Alauda arvensisAlauda International (2004), ‘Prop’ is the assumed proportion of non-migrants for each country (either 0.5 or 1.0), ‘total’ gives the sum of breeding pairs not migrating and ‘%TBP’ the correspondingthe ‘%TBP’ and migrating not pairs breeding of sum the gives countryeach ‘total’ for 1.0), non-migrants or proportionof 0.5 assumed (either the is ‘Prop’ (2004), International common quail ( population. For breeding within percentage the total European standard. Country AL AT BE BG CH CS CZ DE ES FR GB GR HR HU IE IT MK NL PL RO SI SK TR Total TBP % Superscripts indicate Superscripts values derived from averages of the closest relatives if not stated otherwise. a: Superscript mean (no. 2, 4), b: mean (no. 20, 21), c: mean (no. 23, 25, 27), d: no. 41, e: as BirdLife from derived country per sumed, f: based on pairs breeding of numbers maximum and minimum as given are Data Africa. et al. (2000). 53, 54, 55), p: Aviles 48, 49), n: mean (no. tropical to migrating not pairs breeding of number the of Estimation A2. Table

4 Cramp, S. 1998. The complete birds of the western Palearctic. – Oxford References Univ. Press. Aviles, J. M. et al. 2000. Nest-site selection and breeding success in the del Hoyo, J. et al. 1994. Handbook of the birds of the world. – Lynx roller (Coracias garrulus) in the southwest of the . – Edicions. J. Ornithol. 141: 345–350. Glutz von Blotzheim, U. N. and Bauer, K. M. 1987. Handbuch der BirdLife International 2004. Birds in Europe: population estimates, Vögel Mitteleuropas. – Aula-Verlag. trends and conservation status. – BirdLife International.

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