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Défilé de l'Ecluse - Chevrier, Haute-Savoie (74)
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Surroundings and natural setting

The watchpoint of Fort l'Ecluse dominates a narrow passage eroded by the Rhône river at the eastern end of the Jura range. Situated downstream of lake Léman, at the limit of the plains of Genevois and pays de Gex, the watchpoint is at the foot of the massif of Vuache.

Its location is remarkable for observing the autumn migration of raptors, but also for stork migration (20.000 birds on average are counted every year). The migration route following the right bank of Lake Léman or the ridges of the High Jura converges into this bottleneck and migrants concentrate over Fort l'Ecluse.

Ornithological interest

The best observation period starts early July with the first Black Kites and ends in November with the migration of Common Buzzards. The migration survey is conducted daily by volunteers only, weather permitting.

The most abundant migrants include Common Buzzard (11.250 individuals on average), Black Kite (4750) and Honey Buzzard (4575). Red Kite (1650), Sparrowhawk and Marsh Harrier (580) are also well-represented. Less common species such as Osprey, Montagu's Harrier, Merlin, etc. are observed annually but in smaller numbers. Among the rarities, Greater Spotted Eagle is observed every year and Pallid Harrier has been noted once. Booted Eagles and Lesser Spotted Eagles may also be encountered.

Besides the raptors, an impressive list of migrants has been noted at Fort l'Ecluse, ranging from Great White Egret to Chaffinch, over Woodpigeons and Stock Doves. Black Storks and White Storks are also seen regularly, with between 80 and 180 Black Storks a year.

The first observations from the fortress, which still is a very good watchpoint, date back to the 1960s. Although birds can be observed at short range from there, the rather limited view is hampering a good census. With the arrival of scopes, birders started to count from Chevrier, facing the defile, allowing almost exhaustive counts.


Take the RN 206 Valleiry-Bellegarde-sur-Valserine. At the exit Vulbens, go straight on, drive under the railway and take a tarmac road immediately on the left. Park your car after 300 m. 


Ligue pour la Protection des Oiseaux délégation Haute-Savoie
24, rue de la Grenette
74370 Metz-Tessy
Tel. : 04 50 27 17 74
Email :

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