‘Most Animals Move Around’: Environmental Impact Assessments Underestimate Harm on Migratory Birds and Other Wildlife

An Environmental Impact Assessment (EIA) is an essential tool used to identify the likely environmental — as well as socio-economic and cultural — impacts of a proposed project or development prior to decision making. The purpose of the report is to find ways to reduce adverse impacts by providing information and options to those making decisions so that they will be better equipped to tailor projects to fit the local environment.

A new study conducted by a team of researchers from universities in Portugal, Iceland and England demonstrates the fallibility of some EIAs.

In the study, the research team demonstrated that more than 10 times the number of a specific bird — the Black-tailed Godwit — than was estimated in an earlier EIA would be affected by a potential airport development in Portugal, a press release from the University of East Anglia (UEA) said.

“Environmental Impact Assessments are carried out when developments are planned for sites where wildlife is protected. But the methods used to produce these reports seldom consider how species move around between different sites. This can drastically underestimate the number of animals impacted and this is particularly relevant for species that are very mobile, like birds,” said professor Jenny Gill of the UEA School of Biological Sciences in the press release.

The study, “Conservation beyond Boundaries: using animal movement networks in Protected Area assessment,” was published in the journal Animal Conservation.

Black-tailed Godwits have been the research team’s subjects for more than three decades, but the scientists point out that the Godwits, like any migrating species, tend to be underrepresented by EIAs.

“Put simply, the problem arises when assessments treat animals, which move, as if they were permanently fixed to one spot,” Josh Nightingale, Ph.D. of the University of Aveiro in Portugal, a researcher in UEA’s School of Biological Sciences, told EcoWatch in an email. “EIAs typically calculate the potential impact of a development by counting animals within the area predicted to be affected. This approach ignores connectivity – that is, animals will often move between several sites within a given area. Therefore, the total number of individual animals using the area in question might be far higher than the number present at the moment of the count, much like the number of people in a shop at a given moment will be lower than the number of people that use it regularly.”

Counting individual birds at a fixed location and time without considering how their movements fluctuate flies in the face of their natural migratory tendencies.

“We used records of individual birds’ local movements to understand how they use the whole landscape, including both the area directly affected by the proposed airport and its surroundings. We see patterns of daily and seasonal changes in who visits those areas, such that over the course of a year far more individuals visit the affected sites than counts suggest,” Nightingale said.

The researchers studied Portugal’s Tagus Estuary, a large coastal wetland where an environmental license had already been given for the construction of the new airport.

“This area is Portugal’s most important wetland for waterbirds, and contains areas legally protected for conservation. But it faces the threat of having a new international airport operating at its heart, with low-altitude flightpaths overlapping the protected area,” Nightingale said in the press release. “Black-tailed Godwits are one of several wading birds that we see in large numbers on the Tagus. The new airport’s Environmental Impact Assessment estimated that under six per cent of the Godwit population will be affected by the plans. However, by tracking movements of individual Godwits to and from the affected area, we found that more than 68 per cent of Godwits in the Tagus estuary would in fact be exposed to disturbance from aeroplanes.”

The scientists found that specific sites are important to individual birds and are not interchangeable with locations unknown to them.

“We also see that each individual bird depends on a small, unique set of sites throughout their lives (which may be several decades long). This means it’s unlikely that they can easily switch to using other, unfamiliar areas,” Nightingale told EcoWatch. “Our method finds impacts on ten times more [G]odwits than the developers’ study – given what we know about how these birds move around, our figures seem a more realistic estimate of the airport’s impact.”

The researchers also said the environmental impact of a dam-like structure across the Wash estuary in the UK — called a tidal barrage — had been greatly underestimated.

The researchers found that the tidal barrage would not only be much more damaging than initially thought for the wild birds who frequent it, but also for England’s biggest colony of common seals.

“This doesn’t just affect migratory birds – most animals move around, and often depend on patchy resources, even if they use them infrequently. Examples would include a safe place to roost at high tide, or a watering hole in the savannah, used by animals that also feed in other sites over much larger areas,” Nightingale told EcoWatch.

The locations of individual Godwits were tracked throughout their lifetimes with the aid of a network of citizen scientists throughout Europe.

“The project began in the early 1990s, and was designed to understand how individuals use sites across a migratory range, and how migratory ranges can change over time. On their annual journeys, these are birds that connect sites across vast distances, which means that conserving their populations is challenging and typically requires international cooperation,” Nightingale said. “One example of this international cooperation is the network of volunteer ringers and observers who contribute to this project, by marking birds and collecting observations of their movements. Studies like ours benefit enormously from the enthusiasm and dedication of these volunteers.”

In order to track the Godwits, the researchers fitted them with different combinations of colorful leg rings.

“Many of these Godwits spend the winter on the Tagus Estuary,” said Dr. José Alves, a researcher at the University of Aveiro and visiting academic at UEA’s School of Biological Sciences, in the press release. “So we used local sightings of colour-ringed birds to calculate how many of them use sites that are projected to be affected by airplanes. We were then able to predict the airport’s impact on future Godwit movements across the whole estuary.”

Alves added that this strategy could be used to predict the effects of many other potential projects.

“This method of calculating the footprint of environmental impact could be applied to assess many other proposed developments in the UK, particularly those affecting waterbirds and coastal habitats where tracking data is available,” Alves said.

While EIAs work well in some aspects of impact assessment, Nightingale said they could be improved.

“EIAs are extremely important for assessing the impacts of developments, particularly when conducted with the best available evidence. Currently, the requirements of EIAs are often too limited to allow the true impacts to be revealed, and despite being obliged to use the ‘best available evidence,’ that is not always done. But that means we need to improve them rather than lose them. Not considering movements of target species is a major limitation of EIAs, and our new method is intended to help plug this gap,” Nightingale told EcoWatch.

Alves hopes the data from the study will help with a current lawsuit against the proposed airport development in Portugal.

“Eight environmental NGOs together with Client Earth have already taken the Portuguese government to court to contest the approval of this airport development. We hope our findings will help strengthen the case by showing the magnitude of the impacts, which substantially surpass those quantified in the developer’s Environmental Impact Assessment,” Alves said in the press release.

Nightingale pointed out that, while the public is increasingly in favor of conservation, and scientific discoveries concerning the effects of humans on our planet show the dire need for increased stewardship of our ecosystems, political leaders often fall short.

“I think the conservation sector’s ambitions are growing, alongside public support and scientific understanding. That is all great news for nature. Political and regulatory mechanisms are lagging far behind, though,” Nightingale told EcoWatch. “There’s little point in grandly announcing an intention to protect 30% of the planet in 7 years (as was promised at the CBD COP last December in Montreal), if existing protected areas with national, European and international designation can be disturbed by short-haul flights, like the Tagus, or sucked dry by fruit farmers, as has happened to Doñana in Spain. We urgently need our politicians to understand the costs of degrading our ecosystems, and to act now to protect and restore them.”