A new study reveals that population declines in migratory birds have been greatest among species that migrate to areas with more human infrastructure – roads, buildings, power lines, wind turbines – as well as higher population densities and hunting levels.

Dr James Gilroy, from the University of East Anglia’s (UEA) 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.”

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.

Dr C,laire Buchan from UEA’s School of Biological Sciences, explained:

“We found that human modification of the landscape in the birds’ distribution ranges in Europe, Africa and Western Asia is associated with declining numbers of over 100 Afro-Eurasian migratory birds.

“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.”

The research was led by UEA (UK) in collaboration with the University of Porto and the University of Lisbon (both Portugal), and the Czech Society for Ornithology (Czech Republic).

Researchers working on this project have received funding from the Natural Environment Research Council (NERC), the European Commission and the Portuguese Foundation for Science and Technology.

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.”

‘Spatially explicit risk mapping reveals direct anthropogenic impacts on migratory birds’ was published in the journal Global Ecology and Biogeography on June 25, 2022.