| 1. |
- Andueza, Miren, et al.
(författare)
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Connectivity in Reed Warblers Acrocephalus scirpaceus between breeding grounds in Europe and autumn stopover sites in Iberia
- 2013
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Ingår i: Ardea. - : Netherlands Ornithologists' Union. - 0373-2266. ; 101:2, s. 133-140
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Tidskriftsartikel (refereegranskat)abstract
- We determined the degree of connectivity in the Eurasian Reed Warbler Acrocephalus scirpaceus between breeding regions in central and northern Europe and stopover sites in Iberia, during the autumn migration. We used both recovery data and wing length analyses to achieve this. Biometric data were obtained during 2009 at 11 sampling localities in Iberia, which we amalgamated into four major migratory areas within the region (Central, Western, Eastern and Southwestern Iberia, hereafter CI, WI, EI, SW). From the EURING database, we selected birds captured at their breeding sites in Europe and recaptured in Iberia during the autumn migration. Reed Warblers passing through WI had shorter wings than those in CI, EI and SW, suggesting that birds in WI migrated shorter distances, a fact also supported by recovery data. Although Reed Warblers showed some population overlap when passing through Iberia, we found that birds passing through EI and CI came from areas further to the east (continental Europe) than those passing through WI (mainly British Isles), thus supporting parallel migration. Reed Warblers tended to converge in southwestern Iberia, suggesting an effect of nearby geographical barriers.
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| 2. |
- Andueza, Miren, et al.
(författare)
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Geographic variation in body mass of first-year Reed Warblers Acrocephalus scirpaceus in Iberia
- 2014
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Ingår i: Ornis Fennica. - 0030-5685. ; 91:2, s. 88-99
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Tidskriftsartikel (refereegranskat)abstract
- On their route to tropical Africa, European trans-Saharan migrants must cross two major geographical barriers, the Mediterranean Sea and the Sahara Desert, which necessitates the accumulation of large fuel loads. While northern Africa is the chief region where most migrants gain fuel for the Sahara crossing, Iberia is a target area to gain fuel before the sea crossing existing between Europe and Africa. Despite the large body of studies approach- ing the question of fuel accumulation before geographic barriers, it is still poorly known which factors apart from distance to a certain barrier shape the geographical pattern of fuel reserves. To investigate this question in detail we used data of first-year Reed Warblers from 12 localities within Iberia during the autumn migration period of 2009. We run linear models to analyze the effects of location in Iberia, date, and body size on body mass variation at each migratory flyway (eastern, central and western Iberia). Flight ranges from each site were also calculated. Our results showed that Reed Warblers in Iberia had the necessary fuel needed to arrive in northern Africa but not to tropical Africa. However, body mass patterns varied depending on the geographical region (eastern, central or west- ern Iberia). Date did not affect body mass in central and western Iberia, but in eastern Ibe- ria heavier birds tended to pass later. Thus, the factors shaping body mass of Reed War- blers in Iberia before the sea crossing to Africa seemed to be more complex than just the distance to this geographical barrier, with underlying stopover quality-associated factors possibly playing a relevant role.
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| 3. |
- Campos, Ana R., et al.
(författare)
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How do Robins Erithacus rubecula resident in Iberia respond to seasonal flooding by conspecific migrants?
- 2011
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Ingår i: Bird Study. - : Informa UK Limited. - 0006-3657 .- 1944-6705. ; 58:4, s. 435-442
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Tidskriftsartikel (refereegranskat)abstract
- Capsule The majority of Robins in Iberia are sedentary and stay in their nesting areas despite the pre- sumed increased competition that results from the seasonal flooding of the area by conspecific migrants. Aims To evaluate if Robins in Iberia are displaced from their nesting areas by the presence of large num- bers of competitors originating from higher latitudes. Methods Data from constant effort ringing sites were used to estimate the proportion of Robins that are strictly sedentary and the seasonal variation in Robin numbers. Hydrogen stable isotope ratios (d2H) in feathers, and sex ratios determined through molecular techniques, allowed an insight into the numerical importance of invading Robins from higher latitudes. Results Robins were more numerous outside the breeding season, with clear influxes in autumn. Around half of the locally nesting Robins were captured during winter, indicating they are truly sedentary. d2H in feathers suggests that a wide mixture of Robins from all European latitudes were present in winter, and these data, together with sex ratios, suggest that there may be similar numbers of local and foreign individ- uals in winter at the main study site. Conclusion Despite the occupation of their range by migrants, local birds are largely sedentary.
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| 4. |
- Correia, Edna, et al.
(författare)
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Migration strategy of white-spotted bluethroats (Luscinia svecica cyanecula and L. s. namnetum) along the eastern Atlantic route
- 2013
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Ingår i: Ardeola. - : Ardeola. - 0570-7358. ; 60:2, s. 245-259
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Tidskriftsartikel (refereegranskat)abstract
- The bluethroat Luscinia svecica is a particularly interesting species for the study of the mechanisms that control migration because it comprises several recently diverged subspecies that differ in migratory distance and direction. Here we use ringing data to describe the migration strategy and winter distribution of L. s. cyanecula and L. s. namnetum along the eastern Atlantic coast of Iberia and West Africa. No differences were found in autumn migration phenology between subspecies, ages and sexes. However, in contrast to L. s. namnetum, the mean wing length of L. s. cyanecula decreased and its body mass increased during this migratory period. The subspecies also differed in migration speed and stopover behaviour, with L. s. cyanecula travelling faster and refuelling during stopovers. The potential non-stop flight range was greater in L. s. cyanecula and increased with decreasing latitude, which is probably related to the need to overcome geographical barriers to reach the wintering grounds. During winter, the birds captured in sub-Saharan Africa were almost exclusively L. s. cyanecula, whereas L. s. namnetum wintered mainly in Iberia, and the probability of capturing adults increased with decreasing latitude. L. s. cyanecula captured in Africa had longer wings than those migrating through and wintering in Iberia, indicating a leapfrog migration pattern also within L. s. cyanecula populations.
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| 5. |
- Kvist, Laura, et al.
(författare)
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Endangered subspecies of the Reed Bunting (Emberiza schoeniclus witherbyi and E. s. lusitanica) in Iberian Peninsula have different genetic structures.
- 2011
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Ingår i: Journal of Ornithology. - : Springer Science and Business Media LLC. - 2193-7192 .- 2193-7206. ; 152:3, s. 681-693
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Tidskriftsartikel (refereegranskat)abstract
- In the Iberian Peninsula, populations of two subspecies of the Reed Bunting Emberiza schoeniclus have become increasingly fragmented during the last decades when suitable habitats have been lost and/or the popula- tions have gone extinct. Presently, both subspecies are endangered. We estimated the amount of genetic variation and population structure in order to define conservation units and management practices for these populations. We found that the subspecies lusitanica has clearly reduced genetic variation in nuclear and mitochondrial markers, has a drastically small effective population size and no genetic differentiation between populations. In contrast, the sub- species witherbyi is significantly structured, but the popu- lations still hold large amounts of variation even though the effective population sizes are smaller than in the non- endangered subspecies schoeniclus. We suggest several management units for the Iberian populations. One unit includes subspecies lusitanica as a whole; the other three units are based on genetically differentiated populations of witherbyi. The most important genetic conservation mea- sure in the case of lusitanica is to preserve the remaining habitats in order to at least maintain the present levels of gene flow. In the case of the three management units within witherbyi, the most urgent conservation measure is to improve the habitat quality to increase the population sizes.
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| 6. |
- Mátrai, Norbert, et al.
(författare)
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Do the European Great Reed Warblers (Acrocephalus arundinaceus) reach South Africa during wintering?
- 2012
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Ingår i: Journal of Ornithology. - : Springer Science and Business Media LLC. - 2193-7192 .- 2193-7206. ; 153:2, s. 579-583
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Former studies have shown that the Great Reed Warbler (Acrocephalus arundinaceus) has two genetically distinguishable haplogroups (a ‘‘western’’ and an ‘‘eastern’’ clade). The species occurs in South Africa from January to late March, yet, in the whole database of EURING, there are no recoveries to the south of the Congo. There are at least three hypotheses concerning which birds are seen wintering in South Africa: (1) the European breeders reach South Africa, but there are no ringing recoveries; (2) a mixed population of birds originating from Turkey, Iran and Kazakhstan (Near and Middle East) winters in South Africa; and (3) birds from Europe and the Near and Middle Eastern populations both reach South Africa. We have sequenced a 492-bp part of the mtDNA control region II in 146 samples from five European breeding and one South African wintering population of Great Reed Warblers. The results show that over 60% of the wintering birds in South Africa carry European haplotypes, belonging to both ‘‘eastern’’ and ‘‘western’’ clades. Since the exact haplotypic constitution of the Near and Middle Eastern populations are not known to us, we cannot exclude that a mixed wintering population is formed from birds originating from these regions, but it seems more likely that the European breeders reach South Africa.
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| 7. |
- Neto, Julio, et al.
(författare)
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Biometrics and sub-specific identification of white-spotted Bluethroats (Luscinia svecica cyanecula and L. s. namnetum) during autumn and winter.
- 2012
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Ingår i: Ardeola. - 0570-7358. ; 59:2, s. 309-315
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Detailed analyses of the biometrics of white-spotted bluethroats captured in the Iberian Peninsula and sub-Saharan Africa show that previous criteria for diagnosing subspecies are inadequate. This deficiency seems to result from feather wear during the breeding period and so new criteria are proposed for the migratory and wintering periods. Foreign recoveries in Portugal indicate that the new criteria work better during these periods but, a small proportion of misidentifications are still likely to occur. As bimodality is shown by biometric traits other than wing length, further refinements should consider the use of multiple traits as well as genetic markers.
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| 8. |
- Neto, Julio, et al.
(författare)
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Distribution, phenology and condition of Aquatic Warblers Acrocephalus paludicola migrating through Portugal.
- 2010
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Ingår i: Ardeola. - 0570-7358. ; 57:1, s. 181-189
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Tidskriftsartikel (refereegranskat)abstract
- We show that the low number of aquatic warblers Acrocephalus paludicola ringed in Portugal is explained by the low ringing effort, and that Portugal is an important country for its migration. Most of the seven sites where the species was detected are recognized for their biological importance and protected. There seemed to be a decline in the number of birds caught, particularly of juveniles, which might be associated with a decline in breeding success. All aquatic warblers were captured in August and September, showing a peak at the end of August, and adults migrated significantly earlier than juveniles. Both age classes significantly increased in body condition during the season. The potential non-stop flight range varied substantially between individuals: some birds would be able to migrate to the wintering quarters without refueling, but the low flight range of many individuals suggests that some fueling takes place in Portugal.
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| 9. |
- Neto, Julio, et al.
(författare)
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Low frequency of extra-pair paternity in Savi's Warblers (Locustella luscinioides)
- 2010
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Ingår i: Behaviour. - 1568-539X. ; 147:11, s. 1413-1429
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Tidskriftsartikel (refereegranskat)abstract
- Although the frequency of extra-pair paternity (EPP) has been described for many species, the relative importance of the various contemporary and historical factors explaining EPP variation is still the subject of debate. In this study, we found 11 polymorphic microsatellite loci in the Savi's Warbler (Locustella luscinioides), and used eight loci to analyze the paternity of 392 nestlings belonging to 102 broods of this little-known species. The frequency of EPP was 4.1% of nestlings and 5.9% of broods, which is surprisingly low given what is known about Savi's Warbler's life history and ecology, and among the lowest found of any socially-monogamous passerine bird. Comparisons with similar species indicate that this low frequency is unlikely to have been determined by the ancient evolution of life history strategies. Our observations suggest that the costs of engaging in extra-pair copulations might be high for the females. Larger males, particularly those with longer bill and tarsus, are more likely to be cuckolded; and the few possible comparisons between cuckolded males and extra-pair sires reveal a similar pattern. We further show that bill and tarsus lengths correlate with arrival date, which is associated with individual quality in many migratory bird species.
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| 10. |
- Neto, Julio, et al.
(författare)
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Phenotypic Divergence among West European Populations of Reed Bunting Emberiza schoeniclus: The Effects of Migratory and Foraging Behaviours
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:5
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Tidskriftsartikel (refereegranskat)abstract
- Divergent selection and local adaptation are responsible for many phenotypic differences between populations, potentially leading to speciation through the evolution of reproductive barriers. Here we evaluated the morphometric divergence among west European populations of Reed Bunting in order to determine the extent of local adaptation relative to two important selection pressures often associated with speciation in birds: migration and diet. We show that, as expected by theory, migratory E. s. schoeniclus had longer and more pointed wings and a slightly smaller body mass than the resident subspecies, with the exception of E. s. lusitanica, which despite having rounder wings was the smallest of all subspecies. Tail length, however, did not vary according to the expectation (shorter tails in migrants) probably because it is strongly correlated with wing length and might take longer to evolve. E. s. witherbyi, which feed on insects hiding inside reed stems during the winter, had a very thick, stubby bill. In contrast, northern populations, which feed on seeds, had thinner bills. Despite being much smaller, the southern E. s. lusitanica had a significantly thicker, longer bill than migratory E. s. schoeniclus, whereas birds from the UK population had significantly shorter, thinner bills. Geometric morphometric analyses revealed that the southern subspecies have a more convex culmen than E. s. schoeniclus, and E. s. lusitanica differs from the nominate subspecies in bill shape to a greater extent than in linear bill measurements, especially in males. Birds with a more convex culmen are thought to exert a greater strength at the bill tip, which is in agreement with their feeding technique. Overall, the three subspecies occurring in Western Europe differ in a variety of traits following the patterns predicted from their migratory and foraging behaviours, strongly suggesting that these birds have became locally adapted through natural selection.
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| 11. |
- Neto, Julio, et al.
(författare)
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Phylogeography of a Habitat Specialist with High Dispersal Capability: The Savi’s Warbler Locustella luscinioides
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- In order to describe the influence of Pleistocene glaciations on the genetic structure and demography of a highly mobile, but specialized, passerine, the Savi’s Warbler (Locustella luscinioides), mitochondrial DNA sequences (ND2) and microsatellites were analysed in c.330 individuals of 17 breeding and two wintering populations. Phylogenetic, population genetics and coalescent methods were used to describe the genetic structure, determine the timing of the major splits and model the demography of populations. Savi’s Warblers split from its sister species c.8 million years ago and have two major haplotype groups that diverged in the early/middle Pleistocene. One of these clades originated in the Balkans and is currently widespread, showing strong evidence for population expansion; whereas the other is restricted to Iberia and remained stable. Microsatellites agreed with a genetic break around the Pyrenees, but showed considerable introgression and a weaker genetic structure. Both genetic markers showed an isolation-by-distance pattern associated with the population expansion of the eastern clade. Breeding populations seem to be segregated at the wintering sites, but results on migratory connectivity are preliminary. Savi’s Warbler is the only known migratory bird species in which Iberian birds did not expand beyond the Pyrenees after the last glaciation. Despite the long period of independent evolution of western and eastern populations, complete introgression occurred when these groups met in Iberia. Mitochondrial sequences indicated the existence of refugia-within-refugia in the Iberian Peninsula during the last glacial period, which is surprising given the high dispersal capacity of this species. Plumage differences of eastern subspecies seemed to have evolved recently through natural selection, in agreement with the glacial expansion hypothesis. This study supports the great importance of the Iberian Peninsula and its role for the conservation of genetic variation.
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| 12. |
- Neto, Julio, et al.
(författare)
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Sex allocation in Savi’s Warblers Locustella luscinioides: multiple factors affect seasonal trends in brood sex ratios.
- 2011
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Ingår i: Behavioral Ecology and Sociobiology. - : Springer Science and Business Media LLC. - 1432-0762 .- 0340-5443. ; 65:2, s. 297-304
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Tidskriftsartikel (refereegranskat)abstract
- Sex allocation theory predicts that whenever the relative fitness of sons and daughters differ, females should invest more in the sex with the greatest fitness return. In this study, we evaluated the influence of various ecological factors on the brood sex ratio (BSR) of Savi’s warblers (Locustella luscinioides) across several breeding seasons. There was a slight but significant female production bias at the population level, which is consistent with the ‘local resource competition’ hypothesis, as the breeding density is very high and females are more prone to disperse. We found that there was a significant decline in BSR during the breeding season, but no influence of male size, female size, social status nor extra-pair paternity were detected. The seasonal decline in BSR was further evaluated by assessing the within- and between-female effects, which indicated that multiple factors were operating simultaneously in our study population. First, there was a significant within- female decline in BSR, which was consistent with the decline in female condition due to the reproductive effort associated with multiple brooding (supporting the Trivers and Willard hypothesis). Second, a significant decline in BSR with the laying date of first clutches of different pairs indicated that male and/or female qualities are also associated with the seasonal variation in BSR. Finally, a comparison between the sex of the youngest nestling with the remaining ones did not suggest any bias, indicating that females do not compensate for the increased mortality of the last nestling (caused by asynchronous hatching) by producing a male from the last laid egg.
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| 13. |
- Neto, Julio, et al.
(författare)
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Variation in body condition of breeding Savi's Warblers Locustella luscinioides: the reproductive stress and flight adaptation hypothesis revisited
- 2010
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Ingår i: Journal of Ornithology. - : Springer Science and Business Media LLC. - 2193-7206 .- 2193-7192. ; 151:1, s. 201-210
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Tidskriftsartikel (refereegranskat)abstract
- Current theory suggests that mass change in adult birds while breeding may be adaptive (to reduce wing-loading during nestling feeding) or result from physiological stress. To test which might be more important in determining mass loss in breeding Savi's Warblers (Locustella luscinioides), we used a new approach in which the variation in four indices of body condition was described: weight, fat score, muscle score and lean weight (i.e. excluding fat and muscle). We expected weight variations to be adaptive if they involved changes in fat and lean weight, whereas physiological stress should influence the muscle score to a greater extent. As in other species, females showed a greater variation in weight, and carried more fat, than males during the breeding cycle. During incubation, females had greater weight and fat score than males. The weight remained constant and lean weight declined in both sexes, whereas females increased in muscle, which probably reflects the regression of the reproductive organs. During the nestling stage, both sexes declined significantly in all four indices of condition, showing evidence of physiological stress. However, the greater decline in weight in females than in males is consistent with the flight-adaptation hypothesis, as are the cyclic changes in lean weight associated with the various nesting attempts. The fact that both sexes declined significantly in weight, muscle and lean weight with an increasing number of nesting attempts, but not in fat, which was recovered after each nestling period, also indicates that both reproductive stress and adaptive changes occur during breeding. When the whole breeding season was considered, females showed a greater decline in muscle than males, which we interpret to be evidence for a greater reproductive stress in females. We suggest that the small breast muscle size and depleted protein reserves at the end of the breeding period might influence future survival through impaired flight ability and a compromised post-breeding moult.
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| 14. |
- Prochazka, Petr, et al.
(författare)
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Using stable hydrogen isotopes (delta H-2) and ring recoveries to trace natal origins in a Eurasian passerine with a migratory divide
- 2013
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Ingår i: Journal of Avian Biology. - 0908-8857. ; 44:6, s. 541-550
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Tidskriftsartikel (refereegranskat)abstract
- Despite recent advances in technology, it remains difficult to connect breeding and non-breeding areas of populations of migratory organisms due to the challenges of year-round tracking. Here, we used the Eurasian reed warbler Acrocephalus scirpaceus, a passerine with a pronounced migratory divide to demonstrate the promise of integrating several sources of information within the Bayesian modelling framework for the study of migratory connectivity. To this end, we combined data from stable hydrogen isotope ratios (H-2) of feathers, ring recoveries, and the geographic delineation of sub-populations on either side of the migratory divide. Feather H-2 measurements from local juvenile birds sampled across the breeding range tightly correlated with amount-weighted mean annual precipitation H-2 values predicted for the natal sites. Predicted natal origins of birds intercepted en route in the Mediterranean region largely differed among the five stopover sites. Thanks to the different migratory pathways used by different breeding populations and the existence of a migratory divide, we were able to effectively narrow the assigned regions of origin. Our results show that spatial resolution of likelihood-based assignments of geographic origins based on H-2 measurements may improve significantly when prior probabilities derived from population-specific migratory directions are included. Integrating information from stable isotopes, ring recoveries, geolocators and other sources within the Bayesian modelling framework will provide an extremely useful toolbox for the study of animal movements in the future.
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