Migração das Hydroprogne caspia

pedro121 escreveu:Tal como os Guinchos devem fazer a migração pelos rios, ou mesmo via Mediterrâneo e depois atravessando a Europa?

eu tenho registos na lagoa de Óbidos de aves em migração, mas curiosamente não tenho em Peniche, isso pode querer dizer que atravessam o istmo como os garajaus-comuns, ou então são tão escassas que nunca calhou.

pedrocardia escreveu:No eBird há muitas observaçães desta espécie no centro da Europa.
Elas podem atravessar pelo centro, seguindo rios e lagos, chegar ao mediterrâneo e só depois rumarem ao nosso país.

Pedro

You are right: from our GPS-tracked bird we know that the terns migrate over land (SW from the Baltic Sea) to the Iberian peninsula. En route some individuals can get in contact with the "Atlantic coast" in The Netherlands and/or France, but from here south every individual we have tracked have continued directly over Spain to Algarve/Cadiz rather than along the coast.

Thus, your observations from northern Portugal (the species being rare there) seem to reflect a real situation.

The Caspian Terns doesn't migrate along the coasts so much. They can follow the but also chose to go inland.

The Caspain terns doesn't migrate on a wide front but instead they follow certain routes. Theres 2/3 route that passes Spain/Portugal.

The most western route Goes via Ijseel Meer in the Netherlands and then to inner part of Bay of Biscay and then strait inland down to Spain/Portugal border areas like Huelva/Monte Gordo/Cadiz and so on. This can been seen on the Map of bird FA06's migration Autumn 2018. This route is not so very common.

The other two routs goes via inner France to Camargue area and then follow Spanish cost in the Mediterranean sea coast line. For the birds that winter in Spain They go inland some where at Valencia the overland to Southern Portugal/Cadiz areas (See tern UA02)... The others follow the Spanish coast and goes over to Africa and then down to Winter areas in Sengal/Gambia area (See bird UA01). This is the most common route for Swedish Caspain Terns even though quite a few also winters in Nigera, Tchad and in the Alexandria-Port Said area in Egypt.

Preferred wintering areas are like approx.
10% in Spain/Portugal
40% in Senegal
25% in Mali
10 % in Tchad
15 % in Egypt

This is the answer why you don't see any Caspians in western Portugal. The Caspians are also a great rarity in England...

Marcio Cachapela escreveu:Interessante. Já observei aves no Sitio das Hortas, Zambujal e recentemente nas salinas das prais do sado. Parece ficar um bocado fora de rota. Quer dizer o quê? Que as aves chegam cá para invernar tendencialmente para o sul de Portugal e Espanha e depois dispersam?