Birds undertake epic migrations across the globe. Knowing no borders, they connect many countries – and even the seas beyond national jurisdictions – in the search for safe heavens where to rest, refuel and spend the winter. But these are no easy journeys. Migratory birds face multiple threats and many populations across the world are facing steep declines.

Conserving migratory birds is thus a shared challenge that hinges on close cooperation between countries. Unfortunately, more often than not, this is not the reality, and poorly thought decisions made by single governments can jeopardize conservation efforts taking place in distant countries.

This is the case of a bird from the Netherlands and an airport (to be) in Portugal.

A bird from the Netherlands.

The bird is the Black-tailed Godwit (Limosa limosa), or ‘Grutto’. Featured in paintings of Rembrandt and Vermeer, the godwit is a national symbol of the Netherlands, and its repetitive ‘grutto-grutto-grutto’ call is still common across the agricultural meadows of the country. However, the species is vulnerable, and the Dutch population has declined by nearly 75% during the last 50 years, mostly due to intensification of agriculture in the breeding areas. Still, the Netherlands are the most important area for the species in Europe and billions of euros in agri-environmental schemes have been invested for its conservation.

Godwits in the meadows of the Netherlands (Dutch Postage Stamp, 1984); source:

Godwits are long distance migratory birds. After the breeding season, in late July, godwits fly to Senegal and Guinea-Bissau where they spend the rest of the year enjoying the plenty of food and the warmer temperatures of coastal Western Africa. Early in the following year, it is about time for the godwits to start traveling back towards their breeding meadows in the Netherlands. But first, many of them make a half-way strategic stopover in the Tagus estuary near Lisbon.

During a single year, the ‘Dutch’ godwits connect, and are affected by the policies, of several countries between Europe and Africa.

The Tagus estuary, Portugal.

Godwits arrive to the Tagus estuary during January. For about one month, they take advantage of the mild weather, to prepare themselves for the challenges of the breeding season ahead. By early March more than 50 000 ‘Dutch’, ‘Icelandic’, ‘German’ and ‘UK’ godwits have used in the mud flats and rice fields of the Tagus estuary. But not only the godwits congregate here, also fond of the estuary are thousands of dunlins, grey plovers, redshanks, avocets, ringed plovers and flamingos, that either winter or stopover before returning to their breeding destinations. From August through February, the Tagus estuary harbours more than 30 000 birds every month!

The Tagus estuary is one of the most important wetlands in Europe and is classified as a Special Protection Area under the European Birds Directive.

A flock of thousands of Black-tailed godwits in the Tagus estuary (Afonso Rocha)

However, not only birds congregate in and around the estuary. Lisbon is a charming city very sought by international tourism. Only in 2018, Lisbon attracted 5.2 million tourists generating millions of euros. Most tourists arrive to the city by plane and there is a pressing need for a new airport. While the needs for a new airport does not seem to be an issue, the location chosen by the Portuguese government for the new airport is a contentious one that spans the national borders.

The new airport: long story short.

As you may expect, the chosen location for the new airport is right in the estuary, in the vicinity of several important foraging and refuge sites used by thousands of migratory birds, including the ‘Dutch’ godwits.

As you may predict, the consequences of having airplanes with jet engines constantly landing and taking-off nearby these sites may have important negative effects on birds.

As you may find unbelievable, the estimations of the areas affected by the airplanes’ blast were miscalculated in the Environmental Impact Assessment. Researchers subsequently flagged this mistake during the public consultation of the process. Nevertheless, the Portuguese Environmental Agency decided to authorize the implementation of the new airport based on erroneous calculations.

As you may now hint, the decision on the location of the new airport did not take into account the obvious negative consequences on the natural heritage of the estuary. It did not consider the ecology of the thousands of birds that use the estuary nor did it ponder the repercussions these impacts may have in the biodiversity of other countries. It will likely violate international agreements such as the African-Eurasian Migratory Waterbirds Agreement (AEWA). It was eminently political.

As you may conclude, researchers from Portugal and the Netherlands fear that the impacts expected from the new airport may have been underestimated. That the godwits and other birds will have a hard time finding alternative feeding and roosting areas. That the airport may critically affect the whole European godwit population as well as other species.

What now?

Portuguese researchers joined forces with conservationists to try to stop the construction of the airport in the Tagus estuary, arguing the decision process violated national and international legislation. In the Netherlands, conservationists initiated a petition to stop the construction of the airport based on the potential impacts it may have on their national bird. Furthermore, this case was brought to the attention of the parties to the Convention of Migratory Species (CMS) during the thirteenth meeting of the conference parties recently held in India.

Recently, the expansion of the Heathrow airport was stopped by courts because it was considered to violate the Paris agreement. This example sets an important precedent, showing that more transparent, rational decisions based on the best existing knowledge are possible. The recent European Green deal reinforces this need and, hopefully, will direct governments to take more responsibility towards their international commitments.

When it comes to the management of migratory species, the ‘bird and the airport’ case perfectly illustrates the importance of international cooperation and shows how local political decisions can have serious effects elsewhere. The final decision on the new airport’s location is yet to be made but, unfortunately, the future seems gloomy for the ‘Dutch’ godwits.