This video says about itself:
Colonies of sea birds from as far as Iceland stop along the Iberian coastline to rest and feed. Some will stay the whole winter, while others will continue their annual migration towards Africa. The marshlands are a haven for bird watchers, who relish in the opportunity to observe rare species and collect data on each bird’s migratory patterns.
From BirdLife:
International agreement join-ups flyway conservation
03-11-2008
A new resolution has been agreed which recognises the importance of promoting international cooperation for the conservation of migratory waterbirds and their habitats. The resolution was passed today (3 November 2008) in South Korea at the 10th meeting of the Conference of the Parties to the Ramsar Convention on Wetlands. …Besides shorebirds, many waterbirds in other global flyways are also at great risk including Crowned Cormorant Phalacrocorax coronatus, Vulnerable Slaty Egret Egretta vinaceigula, Damara Tern Sterna balaenarum and Endangered Red-breasted Goose Branta ruficollis in the African Eurasian Flyways and Ruddy-headed Goose Chloephaga rubidiceps and Vulnerable Andean Flamingo Phoenicoparrus andinus in the American flyways.