Buildings and power lines causing ‘huge’ decline in migratory birds across world

Researchers hope their work will help inform how best to target conservation efforts, reports Aisha Rimi

A total of 103 species of migrating birds were studied, including many rapidly declining species like the Turtle Dove and the Common Cuckoo (Getty Images/iStockphoto)

Migratory birds are in “great decline” due to the way humans have modified the landscape over recent decades, according to new research.

The study, carried out by experts at by the University of East Anglia and published in the journal Global Ecology and Biogeography, reveals that population declines have been the greatest among species that migrate to more urban areas.

Habitat degradation and climate change have also contributed to driving long-term declines.

Dr James Gilroy, from UEA’s School of Environmental Sciences, said: “We know that migratory birds are in greater decline than non-migratory species, but it’s not clear why.

“We wanted to find out where in their life cycles these migratory species are most exposed to human impacts.”

The research team identified 16 human-induced threats to migratory birds, including infrastructure associated with bird disturbance and collisions, conversion of land from natural habitat to human land use, and climate change.

The team mapped each of the 16 threats across Europe, Africa and Western Asia using advanced satellite imagery, from which they also created the first-ever large-scale map of hunting pressure across the region.

A total of 103 species of migrating birds were studied, including many rapidly declining species like the Turtle Dove and the Common Cuckoo, using large-scale datasets.

The team calculated “threat scores” for influences such as habitat loss and climate change, across breeding locations, as well as non-breeding ranges.

Looking at the relationships between these threat scores and bird population trends calculated from 1985 to 2018 by the Pan-European Common Bird Monitoring Scheme (PECBMS), researchers found that human modification of the landscape in Europe, Africa and Western Asia was linked to “declining numbers of over 100 Afro-Eurasian migratory birds”.

Dr Claire Buchan from UEA’s School of Biological Sciences, said: “When we talk about modification of the landscape, we mean things like roads, buildings, powerlines, wind turbines – anything that isn’t naturally there.

“One of the biggest impacts seems to be caused by things that would kill a bird outright – for example flying into a wind turbine, a building, being electrocuted on a powerline, hit by a vehicle or hunted.

“We found that exposure to these human-induced ‘direct mortality’ threats in the bird’s wintering ranges are reflected in population decreases in breeding birds.”

Dr Aldina Franco, also from UEA’s School of Environmental Sciences, said: “Our findings are important because we need to understand where declining species are being most impacted by humans across their seasonal migrations. Pinpointing where birds are most exposed to these threats could help us target conservation actions.”