Fuel accumulation, mainly as fatty acids, is one of the main characteristics of migratory, birds. Studying to what extent each population or species manages fuel load and how it varies along routes of migration or bet...Fuel accumulation, mainly as fatty acids, is one of the main characteristics of migratory, birds. Studying to what extent each population or species manages fuel load and how it varies along routes of migration or between seasons （autumn and spring migrations） is crucial to our understanding of bird migration strategies. Our aim here was to analyse whether migratory blackcaps Sylvia atrieapilla passing through northern Iberia differ in their mean fuel loads, rate of fuel accumulation and ＇ potential＇ flight ranges between migration seasons. Blackcaps were mist netted for 4 h-periods beginning at dawn from 16 September to 15 November 2003 - 2005, and from 1 March to 30 April 2004 - 2006 in a European Atlantic hedgerow at Loza, northern Iberia. Both fuel load and fuel deposition rate （this latter assessed with difference in body mass of within-season recaptured individuals） were higher in autumn than in spring. Possible hypotheses explaining these results could be seasonal-associated variations in food availability （likely lower during spring than during autumn）, the fact that a fraction of the migrants captured in spring could breed close to the study area and different selective pressures for breeding and wintering展开更多
The blackcap Sylvia atricapilla shows a complex migratory pattern and is a suitable species for the studies of morphological migratory syndrome,including adaptations of wing shape to different migratory performance.Ob...The blackcap Sylvia atricapilla shows a complex migratory pattern and is a suitable species for the studies of morphological migratory syndrome,including adaptations of wing shape to different migratory performance.Obligate migrants of this species that breed in northern,central,and Eastern Europe differ by migration distance and some cover shorter distance to the wintering grounds in the southern part of Europe/North Africa or the British Isles,although others migrate to sub-Saharan Africa.Based on>40years of ringing data on blackcaps captured during autumn migration in the Southern Baltic region,we studied age-and sex-related correlations in wing pointedness and wing length of obligate blackcap migrants to understand the differences in migratory behavior of this species.Even though the recoveries of blackcaps were scarce,we reported some evidence that individuals which differ in migration distance differed also in wing length.We found that wing pointedness significantly increased with an increasing wing length of migrating birds,and adults had longer and more pointed wings than juvenile birds.This indicates stronger antipredator adaptation in juvenile blackcaps than selection on flight efficiency,which is particularly important during migration.Moreover,we documented more pronounced differences in wing length between adult and juvenile males and females.Such differences in wing length may enhance a faster speed of adult male blackcaps along the spring migration route and may be adaptive when taking into account climatic effects,which favor earlier arrival from migration to the breeding grounds.展开更多
基金supported by a postgraduate fellowship from the Basque Governmentsupported by project CGL2007-61395(Ministry of Education and Science,Government of Spain)
文摘Fuel accumulation, mainly as fatty acids, is one of the main characteristics of migratory, birds. Studying to what extent each population or species manages fuel load and how it varies along routes of migration or between seasons （autumn and spring migrations） is crucial to our understanding of bird migration strategies. Our aim here was to analyse whether migratory blackcaps Sylvia atrieapilla passing through northern Iberia differ in their mean fuel loads, rate of fuel accumulation and ＇ potential＇ flight ranges between migration seasons. Blackcaps were mist netted for 4 h-periods beginning at dawn from 16 September to 15 November 2003 - 2005, and from 1 March to 30 April 2004 - 2006 in a European Atlantic hedgerow at Loza, northern Iberia. Both fuel load and fuel deposition rate （this latter assessed with difference in body mass of within-season recaptured individuals） were higher in autumn than in spring. Possible hypotheses explaining these results could be seasonal-associated variations in food availability （likely lower during spring than during autumn）, the fact that a fraction of the migrants captured in spring could breed close to the study area and different selective pressures for breeding and wintering
文摘The blackcap Sylvia atricapilla shows a complex migratory pattern and is a suitable species for the studies of morphological migratory syndrome,including adaptations of wing shape to different migratory performance.Obligate migrants of this species that breed in northern,central,and Eastern Europe differ by migration distance and some cover shorter distance to the wintering grounds in the southern part of Europe/North Africa or the British Isles,although others migrate to sub-Saharan Africa.Based on>40years of ringing data on blackcaps captured during autumn migration in the Southern Baltic region,we studied age-and sex-related correlations in wing pointedness and wing length of obligate blackcap migrants to understand the differences in migratory behavior of this species.Even though the recoveries of blackcaps were scarce,we reported some evidence that individuals which differ in migration distance differed also in wing length.We found that wing pointedness significantly increased with an increasing wing length of migrating birds,and adults had longer and more pointed wings than juvenile birds.This indicates stronger antipredator adaptation in juvenile blackcaps than selection on flight efficiency,which is particularly important during migration.Moreover,we documented more pronounced differences in wing length between adult and juvenile males and females.Such differences in wing length may enhance a faster speed of adult male blackcaps along the spring migration route and may be adaptive when taking into account climatic effects,which favor earlier arrival from migration to the breeding grounds.
