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Bibliographie
Références
Selas, V.2017
. Autumn irruptions of Eurasian Jay (Garrulus glandarius) in Norway in relation to acorn production and weather. Ornis Fennica94: 92–100
Ulfstrand, S.1963
. Ecological aspects of irruptive bird migration in Northwestern Europe. Proceedings XIIIth International Ornithological Congress: 780–794
En cours de chargement...
En cours de chargement...
A colourful corvid, present year-round across the whole of Europe, with a distribution ranging from N Africa to the Siberian taiga, including the British Isles, but not Iceland
Many populations are sedentary or locally dispersive during the non-breeding season within their region (NW, N, SW, S, etc). However, ringing has revealed some marked movements of Jays, with birds from the N and NW moving S, and some from continental Europe migrating SW. Jays are sighted regularly in numbers at migration observatories near the Baltic Sea and further south. Most recoveries are within a few kilometres, though exceptional long-distance movements (up to 3,000 km) have been noted. There has been almost no ringing effort across southern countries, where the species is most dispersive.
Most old data (nearly 75%) are of birds found dead. However, the development of demographic studies has increased the number of recoveries, with live recaptures accounting for nearly 90% of recoveries after 1990.
Annual Movements for Geai des chênes
The migration of the Jay can be described as irruptive (Ulfstrand 1963, Selas 2017), as numbers fluctuate between years. There are therefore unpredictable, with some invasion years, though they generally occur in early autumn when they are obvious, while spring movements are far more discrete.
Connectivité par mois par région pour Geai des chênes
SW movements of birds breeding in Central Europe are noted from Sep onwards, with increasing recovery distances until Dec. The lack of such recoveries from Feb onwards might be due to the closure of hunting seasons. Sep is the main month where long, directional movements occur - these correspond with changes in food availability and reproductive success within the range.
Selas, V.2017
. Autumn irruptions of Eurasian Jay (Garrulus glandarius) in Norway in relation to acorn production and weather. Ornis Fennica94: 92–100
Ulfstrand, S.1963
. Ecological aspects of irruptive bird migration in Northwestern Europe. Proceedings XIIIth International Ornithological Congress: 780–794