New studies of birds in the Tagus Estuary could compromise Montijo airport
By: Josh Nightingale
Tags: Birds, Science, Portugal, Conservation, Nature

The original article, by Carla Tomás, was published in Portuguese in Expresso. The following is my translation.

The pandemic removed the rush for the new airport in Montijo and, while the government contemplates conducting a strategic environmental assessment of the airport project, new studies are underway on the ground about the avifauna of the Tagus estuary. The objective is to fill the known gaps in the environmental impact assessment, and could service as evidence for the cases proceeding in the courts. Would the Black-tailed Godwit, Redshank or Grey Plover accept new salinas for roosts or repast, as compensation for the damage to their habitat? That’s what a team of researchers from the University of Aveiro intend to find out.

Study of bird behaviour in the Tagus Estuary. The lines represent the movements of about 10 birds of three species during two-and-a-half weeks this autumn. (Image: Camilo Carneiro)

The nights of the new moon are good to catch birds, fit them with a small GPS/UHF transmitter and know how many there are, how they feed, how they rest and where they move to in the Tagus Estuary area. That’s how the last new moon nights were spent by researchers from the Centre for Marine and Environmental Research (CESAM) at the University of Aveiro, in the Tagus Estuary Nature Reserve, as part of their project “WaderTrack — High-precision tracking system of waders”. The objective is to fill the known gaps in the environmental impact assessment that gave a green light to the airport project in Montijo. Coordinated by the biologist José Alves, the project “WaderTrack” began in October and must be finished by the end of the year.

“We capture each bird just once, attach a small, ultralight GPS/UHF transmitter (of 4–5 grams) with solar panels, and, by using this technology, we can map their movements through the daily and tidal cycles through the winter,” José Alves explained to Expresso. To understand where they go and how they get there, they also installed antennas in three important roosts in the Special Protection Area (SPA) of the Tagus estuary, which represent three types of protected habitat: saltmarsh, palustrine lagoons and salinas. The devices have the capacity to register the GPS location of the birds each 30–45 minutes and transmit the information to the receptor antennas, which for their part send the data to software installed on the researchers’ computers.

In this way, they can assess and quantify how the birds interact with the different habitats of the estuary, according to the tides and the time of day. “We have already acquired some knowledge about the ecology of these species and we know that they feed in the intertidal area during low tide and move to roosts in the supralitoral (the transition zone between river and land) during high tide, but we want to remove critical gaps in our current understanding,” explains the biologist. Amongst the priority wader species which they’re studying are the Black-tailed Godwit, the Grey Plover and the Redshank, which pass the winter in the Tagus.

One of the questions they intend to answer, for example, is about the distance they travel between the roosts and the feeding areas currently available, as well as those included as compensatory measures proposed in the declaration of environmental impact that made the Montijo airport feasible. This is because it is not known if the acquisition of new salinas or the rehabilitation of the Mouchão do Póvoa [a wetland island in the estuary — JN] (two of the measures imposed on the concessionary ANA Airports) will have the desired effects.

The airport project adjacent to the estuary is seen as a threat to the habitat and to the more than 200,000 birds which regularly reside in this protected area, to which are added another 100,000 during their migratory routes. The information which the scientists are gathering “will serve to bridge the current gaps in knowledge about these priority species, keeping in mind the improvement of their conservation status, and thus to inform biodiversity conservation policy and reduce current and future threats and pressure,” emphasises José Alves.

New data for court actions

The result of this study will be useful for the proceedings taking place in court against the Montijo airport, namely the action brought to the Administrative Court of the Lisbon circuit by eight Portuguese environmental defence organisations — SPEA [Portugal’s Birdlife Partner — JN], ANP/WWF Portugal, A Rocha Portugal, FAPAS, GEOTA, LPN, ZERO and Almargem, with the support of the international environmental law NGO ClientEarth.

Beyond the study undertaken by the researchers from the University of Aveiro, there are more scientific projects being developed by other entities, such as BirdLife International, which is assessing the behaviour of species that migrate through the East Atlantic.

“Our objective is to annul the favourable Declaration of Environmental Impact emitted by the Portuguese Environment Agency (APA) and it’s helpful to have all the scientific information that allows us to confirm our arguments,” underlines the biologist Joaquim Teodósio, of the Portuguese Society for the Study of Birds (SPEA), reminding that “the data used in the environmental impact assessment that made the Montijo airport viable are over 10 years old and don’t reflect reality”. The Tagus estuary is Portugal’s most important wetland for waterbirds and one of the most important in Europe.

Despite admitting that the Montijo airport project will have “negative, significant, permanent and irreversible impacts of moderate-to-high magnitude on the avifauna of the estuary, due to the disturbance caused by the transit of aircraft, and which have as a consequence the reduction of areas frequented by waterbirds for roosting, feeding and feeding,” the Institute for Nature Conservation and Forests (ICNF) ended up emitting a final statement that was positive with conditions, which permitted the favourable declaration of environmental impact.

Amongst the conditions to try and control the damages, the ICNF imposed on ANA/Vinci [the company behind the proposed development — JN] a series of measures to compensate for the loss of habitat, which include the acquisition and requalification of salinas or the elaboration of studies to “fill the knowledge gaps in the environmental impact assessment.” It remains to be seen if these measures are effective — and studies like the one coordinated by José Alves serve that purpose.

During the assessment of the project, the experts at ICNF underlines that the new airport will “affect about 20% of birds’ feeding area, which puts at stake the integrity of the whole Special Protection Area (SPA)” of the Tagus estuary, potentially leading to new EU litigation proceedings.

To keep up with news on Project WaderTrack, you can follow the Eco-Flyway lab on Twitter: https://twitter.com/eco_flyway/

Josh Nightingale is a PhD student in the Eco-Flyway lab. Also on Twitter: https://twitter.com/Luscinia_joshua