Periodic Reporting for period 1 - BIRDBARRIER (The Importance of Barriers to Bird Migration)
Reporting period: 2018-09-01 to 2020-08-31
Snow buntings Plectrophenax nivalis are the northernmost breeding songbird and the population studied within this project breeds at Svalbard and winter on the plains south of the Ural Mountains. Unlike red-backed shrikes and great reed warblers, snow buntings commonly migrate in flocks and the diurnal schedule of their migration have been discussed (diurnal vs nocturnal flight schedules). Preliminary tracking results shows that the journey back and forth to Svalbard from mainland Scandinavia includes flights on more than 24 h over open Sea and a mixed diurnal and nocturnal flight strategy. The snow buntings also migrate at lower altitudes compared to red-backed shrikes and great reed warblers, possibly as a result of their northern range.
Another aspect of crossing a major barrier is how do birds establish orientation during long flights over areas that lack perceivable landmarks? Songbirds are known to be able to use several different cues to decide migratory directions, among them a magnetic inclination compass, but how and when they use this information during migration is so far unknown. Juvenile birds inherit a migratory direction and distance, and are capable of orientating (finding a direction and keeping it). Adult birds have been shown to be able to correct for displacement during migration, and find the direction to a known area from an unknown position (commonly referred to as true navigation). In order to understand if juvenile birds have the same ability as adult birds to use true navigation, juvenile and adult common cuckoos Cuculus canorus were caught on migration in Rybachy, Kaliningrad, displaced 1800 km east to Kazan, Russia, and released with GPS transmitters. After the displacement both juveniles and adults corrected for the displacement and flew westwards to get back to their natural migratory route, indicating that juvenile cuckoos are, similar to adult cuckoos, able to use true navigation.