Montijo airport: Birds aren’t stupid — and neither are we!
If everyone agrees that science without supporting data is not science, why do we disagree on whether impact assessments lacking data are valid?
There are many opinions about the proposed location for the new Lisbon airport, on the peninsula of Montijo. Opinions about safety criteria, questions about human health, transport and accessibility, and many other aspects. But even if everyone has at least one opinion, facts are facts! The recent declarations from the honourable Secretary of State reveal a profound ignorance of the state-of-the-art of the ecology of avifauna in the Tagus estuary.
To suggest that “the best scientific and technological data” has been used, when tragically this is not the case, and as much has been shown to the Portuguese Environment Agency, is the height of absurdity in the proceedings of Montijo Airport. I am in complete agreement that “science without supporting data is not science”. For that reason I list here scientific studies published with open access — that is, freely available to anybody interested — which indicate that the shorebirds that use the Tagus estuary are extremely faithful to the sites which they use daily, both for feeding and for roosting (during the high-tide period):
- https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.503
- https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0033811
- https://peerj.com/articles/2517/
This is not, therefore, some shaky supposition, but scientifically proven fact. Something that, as far as I know, its opposite is not: “that…they will find other migratory routes, other stopovers, like in the Mouchão [islands in the northwest of the Tagus].” In case it is, here is the public request for that information and the Public Administration that holds it, but it should have already been published in specialist journals, after peer review, as were the data comprehensively demonstrating that shorebirds in the Tagus estuary show high fidelity to the sites they use.
Who holds the most recent scientific data regarding the avifauna of the Tagus estuary, their ecology and use of habitats? It is not the Portuguese Environment Agency, which delegated the topic of Montijo airport’s impacts on birds to the Institute for the Conservation of Nature and Forests (ICNF), and thus protected itself. However, and perhaps because of a lamentable lack of logistical and human resources, it is also not the ICNF which holds the most advanced information on this subject. Truly, the data and the technological and scientific knowledge which best permit the estimation and evaluation of these impacts are those possessed by Portuguese researchers who dedicate themselves to the study of this subject. Unfortunately, many of them were ignored in this process, even after being present in public consultation promoted by the Portuguese Environment Agency. Therefore the most advanced scientific and technological understanding available for the assessment of impacts on avifauna, as they insist on proclaiming, went unused.
An example?
The dynamics of the waders that use the Tagus estuary as a feeding area (namely the intertidal areas: that is, the sediments exposed during low tide) and a roost (the areas above high water, namely saltpans and marshes) follow the rhythm of the tides. The various species of this group of birds move between these habitats searching for food, ideally in a place close to a known roost, such that moving between the two could very probably be the most energetically profitable. In the Tagus estuary, the distance travelled between these two habitats was, up to today, only estimated and published for one species, the Dunlin (Calidris alpina). It would therefore be important to establish these distances for at least some other species which are known to have a distinct diet from the Dunlin, in order to assess the areas affected in a rigorous way. But that wasn’t done; the total absence of field data collection on this subject for the Environmental Impact Assessment (EIA) dictated that the same measurement be applied to all species. However, the tracking already developed with various other species of birds, by various researchers, using for example GPS devices, enables that quantification in a way that would truly be using the best scientific and technological data.
The EIA is very clear regarding avifauna (Annex 6.3, Effects of the Montijo Airport project on the estuarine avifauna and SPA of the Tagus estuary), noting many times throughout the text that there is a lot of information lacking. And seeing as “there is no airport without impacts” (obviously!), shouldn’t the government be worried about doing this assessment in a truly rigorous way?
Another example?
The EIA considered only one study on the effect of noise on bird disturbance, and it was used incorrectly, such that for a volume of 55 decibels (dB) there would be no change in the behaviour of the birds considered. In reality, the original study, which used a pulse of noise lasting only three seconds emitted from an airhorn, showed that at that volume of noise (which in the case of Montijo airport would certainly be caused by the aeroplanes flying over the estuary) at least 5% of birds change their behaviour. This slip-up could have been rectified following the public consultation, where it was identified by various researchers, but that didn’t happen. Instead, it considered only the area impacted by disturbance designated “strong” (≥65 dB) and ignored the remaining areas where bird disturbance effectively occurs (those ≥55 dB). The argument declared by the Honourable President of the ICNF about this decision is that, starting from the 65 dB volume of noise, at least 25% of birds will be induced to take flight as a response.
So, in a flock of 60,000 birds, such as those composed entirely of Black-tailed Godwits currently present within the Special Protection Area of the Tagus estuary, only when 15,000 birds are forced to take flight would the new airport be considered to have had an impact. As an adapted Portuguese saying goes, “When 15 thousand take off, soon 30 or 60 thousand take off!” No wonder, then, that the petition launched by the Dutch Birdlife partner against the Montijo airport already has more than 27,000 signatures. After all, the Black-tailed Godwit is their national bird!
The above lapse results, for example, in a very serious failure of the evaluation of the true impact of noise on the birds that use the intertidal areas to find their food. An estimate that corrects this error predicts that around half (49%) of the feeding area of the estuary would be affected, and not 31% as predicted in the EIA. Shouldn’t the ICNF, in its role as the national authority on nature conservation, defend this point and demand appropriate compensation measures? Why have a National Strategy for the Conservation of Nature and Biodiversity for 2030, when the Council of Ministers underlined in 2018 the necessity of “Improving the state of conservation of our natural heritage”?
The consequence of not using the best scientific and technological data is plain to see. The EIA (considering disturbances only above 65 dB) refers to the total areas affected as: 246 ha (roosts) and 2,357 ha (feeding areas). The Declaration of Environmental Impact [the government document permitting the project to go ahead, with conditions] in turn indicates that the area of disturbance corresponds to “about 1,600 ha…of feeding habitat in the SPA”. The corresponding compensation measure is the “Acquisition of saltpans in a total area at least equal to that subject to strong disturbance, that is 1,467 ha”. Is this 1,467 ha “about 1,600 ha”? This is neither clear nor rigorous. But more importantly, seeing as saltpans serve essentially as roosting areas, the one thing does not substitute the other. How does it benefit these birds to have places to roost during high tide, if they don’t have areas to feed during low tide, for which is shown 1,467 ha of strong disturbance? These areas are both inseparable and indispensable for the species that will be affected, as the best scientific and technological data demonstrate.
In the final reckoning, the question is not whether birds are stupid or not. The fact is that the science indicates unequivocally that an ever greater number of species is found to be declining. I am sure that the responsibility falls to our generation not to contribute even more to erasing the remaining biodiversity remains that was left to us by previous generations. We have to have the boldness and courage to say, enough! Protecting the areas that have been designated for nature conservation is our greatest duty.
Author’s note: I see with sadness the lamentable level of uninformed debate about the proposed Montijo airport. I am talking here only about the predicted impacts on estuarine avifauna, recognising my vast ignorance of the rest of the matter.
Opinion of José Alves, researcher at the researcher at CESAM — the Centre for Marine and Environmental Studies, University of Aveiro.
Twitter: @_JoseAAlves_
Content originally published, in Portuguese, in the newspaper Público, 20th February 2020.
Translated by Joshua Nightingale, PhD student at CESAM — the Centre for Marine and Environmental Studies, University of Aveiro. Twitter: @Luscinia_joshua
