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Development projects outside protected areas (PA) can greatly impact the species conserved in PAs, a new study has pointed out. Environmental impact assessments (EIA) carried out for development projects significantly underestimate the effect of new developments on wildlife, added the study published in journal Animal Conservation April 7, 2023.
Methods used in assessing environmental impact seldom consider how species move around between different sites. This can lead to underestimating the number of animals impacted, especially in the case of species like birds which are very mobile.
Researchers from the University of East Anglia arrived at this conclusion after assessing the ongoing proposal to develop an airport on a partially protected wetland, the Tagus estuary, in Lisbon, Portugal.
The proposed site is of high natural value and an important breeding, wintering and stopover site for migratory waterbird populations in the East Atlantic Flyway. The research evaluated the extent of noise disturbance on black-tailed godwits, a protected migratory wader species.
In 2020, the Portuguese government approved the construction of the new Lisbon international airport at the heart of the Tagus estuary. Intense aircraft traffic, flying at low altitudes during both approach and take-off, is expected to cross the estuary, considerably overlapping the important intertidal foraging areas.
This project could affect the black-tailed godwits more than 10 times than estimated in a previous EIA. While Tagus estuary protected 82.8 per cent of the godwit population for at least some portion of the year, frequent transboundary movements indicated that 61 per cent also used unprotected sites.
It was also found that critical sites ensuring connectivity between separate PAs and the surrounding landscape were outside the protected areas. This indicates the surrounding, unprotected landscape was integral in supporting the godwits, especially during October–December.
Godwits’ frequent transboundary movements mean that 44.6 per cent of the PA’s godwit population and 68.3 per cent of the overall population would be exposed to noise pollution from the proposed airport. This contradicts the EIA estimate of 0.46-5.5 per cent.
The sites crucial to connectivity, including feeding and roosting areas, would receive at least 55 decibels of pollution from aircraft.
The study emphasised that an accurate assessment of the scale of impacts from developments in or near protected areas is to mitigate or prohibit species loss appropriately.
Animal-tracking data can offer feasible opportunities to assess for adverse effects of external developments on such species, the document pointed out.
The construction and operation of the airport would result in the disturbance of several thousand waterbirds. The further urban development due to it, including parking and transportation hubs, will put additional pressure on the site, a complainant submitted in 2020 stated.
It was also suggested that the construction of the airport might result in a loss of up to 30 per cent of the conservation value of this wetland for shorebirds.
Research shows that frequent disturbance by aircraft is known to have fitness costs for waders by increasing their energy expenditure. It may cause permanent avoidance of habitat, with long-term consequences for site occupancy.
Construction of the airport can lead to a loss of up to 30 per cent of the conservation value of the Tagus estuary in terms of intertidal feeding areas of wintering birds alone, a study published by Cambridge University Press in 2021 said.
To secure the integrity of protected areas and the populations they support, there is a need to accurately assess the impacts of developments inside and outside PA boundaries.