Autumn migration and wintering site of a wood warbler Phylloscopus sibilatrix breeding in Denmark identified using geolocation

Abstract Background Basic knowledge of detailed spatiotemporal migration patterns is lacking for most migratory bird species. Using the smallest available geolocator, we aim to map autumn migration and wintering areas of north European wood warblers Phylloscopus sibilatrix and compare the spatiotemporal pattern with recoveries of individuals ringed across Europe. Results A tracked wood warbler migrated south-south-east to sub-Saharan Africa in Sudan and then west-south-west to winter in Côte d’Ivoire. The timing and route fits well within the distribution of ring recoveries although the westward movement after the Sahara crossing is not revealed by the ring recoveries, but only few recoveries south of Sahara exist. Conclusions The surprising westward movement south of the Sahara supplements the overall pattern revealed by ring recoveries and aids our understanding of the connectivity and site dependence in this generally declining species

Activity and migratory flights of individual free-flying songbirds throughout the annual cycle:method and first case study

We describe a method and device ( 66 (max. 73) nocturnal migratory flights (29 flights in autumn and > 37, max. 44, in spring) adding up to a total of > 434 (max. 495) flight hours. Migratory flights lasted on average 6.6 h with maximum 15.9 h. These flights were aggregated into eight travel episodes (periods of 4-11 nights when flights took place on the majority of nights). Daytime resting levels were much higher during the winter period compared to breeding and final part of spring migration. Daytime resting showed peaks during days between successive nocturnal flights across Sahara, continental Africa and the Arabian Peninsula, indicating that the bird was mostly sleeping between these long migratory flights. Annual activity and flight data for free-living songbirds will open up many new research possibilities. Main topics that can be addressed are e.g. migratory flight performance (total flight investment, numbers and characteristics of flights), timing of stationary periods, activity patterns (resting/sleep, activity level) in different phases of the annual cycle and variability in the annual activity patterns between and within individuals

Remarkably similar migration patterns between different red-backed shrike populations suggest that migration rather than breeding area phenology determines the annual cycle

The regular fluctuation of resources across the Globe guides movements of migratory animals. To ensure sufficient reproductive output and maintain viable population sizes, migratory animals should match arrival at breeding areas with local peaks in resource availability. It is generally assumed that breeding phenology dictates the timing of the annual cycle, but this is poorly studied. Here, we use light-level geolocator tracking data to compare the annual spatiotemporal migration patterns of a long-distance migratory songbird, the red-backed shrike, Lanius collurio, breeding at widely different latitudes within Europe. We find that populations use remarkably similar migration routes and are highly synchronized in time. Additional tracks from populations breeding at the edges of the European range support these similar migration patterns. When comparing timing of breeding and vegetation phenology, as a measure of resource availability across populations, we find that arrival and timing of breeding corresponds to the peak in vegetation greenness at northern latitudes. At lower latitudes birds arrive simultaneously with the more northerly breeding populations, but after the local greenness peak, suggesting that breeding area phenology does not determine the migratory schedule. Rather, timing of migration in red-backed shrikes may be constrained by events in other parts of the annual cycle.</p