Autumn migration over the Alpine passes: Col de Bretolet

Passerines by the tens of thousands (pipits, finches, warblers, robins, thrushes), swifts, raptors (honey buzzard, sparrowhawk, kestrel), wood pigeons; 160+ species ringed. Col de Bretolet (Valais/Haute-Savoie border), Col de Jaman (Vaud), Ulmethöchi (Basel Jura), Switzerland.

Best time: 15 Sep – 20 Oct (September to October). Where: Col de Bretolet ringing station (Vogelwarte Sempach), Col de Jaman (above Montreux), Ulmethöchi (Lauwil, Basel-Landschaft) (Switzerland). Time of day: Flight calls stream through the pass from first light, densest in the first 2 h after sunrise before the col breeze, tailing off by 11:00.

• You can go on your own
• Free
• Binoculars helpful
• Sound 4/5

Open it in the interactive calendarSunrise and sunset listening times for the day you pick, and the map.

When is the best time?

Peak: 15 Sep – 20 Oct. Mid September to 20 October; honey buzzards late Aug–early Sept, wood pigeons and finches in October

Active from 1 Aug to 31 Oct (August to October) in a typical year.

Time of day

Flight calls stream through the pass from first light, densest in the first 2 h after sunrise before the col breeze, tailing off by 11:00; nocturnal migration overhead from dusk on clear nights.

• Morning passage: 30 min before sunrise → 11:00
• Nocturnal migration: last light → first light

What will you hear?

Dawn: flight calls of thousands of pipits, chaffinches and siskins funnelling through the pass at head height, robins ticking in the dwarf pines after a night flight; at night, thrush and robin calls overhead against absolute mountain silence.

Binoculars?

Binoculars helpful. Passerines pass at head height through the col; binoculars for raptors and pigeons higher up, ears for the night.

Where to go

• Col de Bretolet ringing station (Vogelwarte Sempach) — 1,923 m, on the French border above Champéry/Barme; 2.5 h walk. Station staffed Aug–Oct; visitors welcome outside the nets, volunteers by application. Map
• Col de Jaman (above Montreux) — Second ringing station (Groupe d'études faunistiques); accessible from Les Avants; also night migration listening. Map
• Ulmethöchi (Lauwil, Basel-Landschaft) — Jura ridge count site (raptors, pigeons, finches) in Sept–Oct; volunteer counters on site. Map

How to go on your own, and what it costs

Bretolet: from Champéry drive or bus to Barme, then 2.5 h on foot to the col (1,923 m); free, and the ringers welcome visitors outside the net lanes; sleep at the Barme cabane for dawn. Col de Jaman: train to Les Avants, walk up. Ulmethöchi: from Lauwil on foot.

Cost: Free.

Field-recording notes

The passes concentrate birds and wind alike: migration runs on a north-easterly (tailwind) which is exactly the wind that ruins recordings, so the trick is the first two hours after dawn before the col breeze rises, tucked below the ridge line on the lee side. Nocturnal flight calls are exceptional here — a high-gain omni pair on a still night gives clean thrush calls with zero traffic (no road on the col). Don't enter the net lanes or the station enclosure; talk to the ringers. Cabane accommodation at Barme; frost from late September.

Sources

• Vogelwarte Sempach – Col de Bretolet project
• Vogelwarte Sempach – 60 years Col de Bretolet
• SAC – Auf Herbstreise: Beringungsstation Col de Bretolet

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More: all spectacles in Switzerland · bird migration hotspots · Switzerland in September · October