The Usefulness of Biometrics for the Study of Avian Connectivity within Europe. A Case Study with BlackcapsSylvia atricapillain Spain
Summary. The use of biometrics in studies of migratory connectivity is still relatively infrequent in Europe. This is partly due to the fact that biometrics is a less accurate tool when compared to ringing recovery data, or such techniques as stable isotope analyses, use of geolocators or satellite telemetry. Combination with one of these (recovery data) allows us to test the usefulness of biometrics in connectivity analyses, as well as to evaluate/quantify the influence of migratory behaviour on phenotypic traits such as flight morphology. We used historical recovery data, together with flight morphology data obtained from a consistent collection protocol during a three-year ringing progra…
The role of extrinsic and intrinsic factors on departure decisions of a long-distance migratory passerine
[EN] Factors determining departure decisions of migrants from a stopover site can be extrinsic and/or intrinsic but the relative role of each of these factors on departure decisions is still poorly known. Date and wind should be the main factors determining departure decisions in a long-distance migrant, which is expected to minimise duration of migration. Date was considered as an intrinsic factor and wind as an extrinsic one. We analysed the capture-recapture data of a long-distance migrant European songbird, the sedge warbler Acrocephalus schoenobaenus,from a stopover site in northern Iberia during the autumn migration period to quantify the relative importance of several factors on emig…
Covariation in population trends and demography reveals targets for conservation action
Wildlife conservation policies directed at common and widespread, but declining, species are difficult to design and implement effectively, as multiple environmental changes are likely to contribute to population declines. Conservation actions ultimately aim to influence demographic rates, but targeting actions towards feasible improvements in these is challenging in widespread species with ranges that encompass a wide range of environmental conditions. Across Europe, sharp declines in the abundance of migratory landbirds have driven international calls for action, but actions that could feasibly contribute to population recovery have yet to be identified. Targeted actions to improve condit…
ESM for Covariation in population trends and demography reveals targets for conservation action
Supplementary methods, results and JAGS code
Importance of Sampling Frequency to Detect Differential Timing of Migration: A Case Study with BlackcapsSylvia atricapilla
Our aim was to assess to what extent detection of differential timing of passage in migrant birds depends on the sampling frequency (SF). We determined if Blackcaps Sylvia atricapilla performed differential migration by age and sex when passing over N Iberia. We mist netted and ringed migrating Blackcaps at a stopover site, both during the autumn (2005) and the spring (2006) migrations. During autumn, adult female Blackcaps passed later than juvenile birds and adult males. In spring, however, migration differed mainly by sex rather than by age. In particular, males passed over earlier than females, likely due to the pressure on males to earlier arrival at their breeding areas. A simulation …
Fuel Load and Potential Flight Ranges of Passerine Birds Migrating through the Western Edge of the Pyrenees
Abstract. The estimation of fuel load and the potential flight ranges of migrant birds are crucial to understanding the ecological and evolutionary significance of bird migration strategies. The movement of migrant birds between Iberia and the rest of Western Europe is thought to be shaped by the Pyrenees and nearby seas. Because of this area's unique geography, the routes of migrants that move to (autumn migration) or from (spring migration) Iberia tend to pass through the western and eastern edges of the Pyrenees. Fuel-load analyses and the assessment of potential flight ranges from these edges can provide insights about the extent of Iberia's use as a consistent stopover and fuelling are…
Fuel load and flight ranges of blackcaps Sylvia atricapilla in northern Iberia during autumn and spring migrations
Abstract 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 atricapilla 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 - 20…
Patterns of migration and wintering of RobinsErithacus rubeculain northern Iberia
The aim of this study was to analyse the patterns of migration and wintering of European Robins Erithacus rubecula in northern Iberia (Plaiaundi Ecological Park, Irun, N Spain). Overall, 185 Robins were ringed at weekly trapping sessions from September 2004 to April 2005. The temporal distribution of abundance and recaptures indicated that the autumn migration period lasted from September to November, the winter period from November to February, and the spring migration from March to April. Some wintering Robins arrived earlier than most of the migrants which passed through the area in autumn, whilst most left the area before the majority of spring migrants appeared. First‐winter Robins wer…
Deteriorating Weather Conditions Predict the use of Suboptimal Stopover Sites by Aquatic WarblersAcrocephalus paludicola
Abstract. The Aquatic Warbler Acrocephalus paludicola is a globally threatened songbird and its decline is related to habitat loss. Accordingly, most studies dealing with the stopover ecology of this species have been chiefly focused on the habitat use and the availability of suitable habitats along its route of migration. In contrast, much less attention has been paid to other environmental causes potentially explaining the use of stopover sites. Our aim here was to investigate whether the Aquatic Warbler at an apparently suboptimal stopover site with small area of suitable habitats stops over only during adverse weather conditions. We used data obtained at a suboptimal (Jaizubia marshland…