Migratory birds are declining globally because of the way humans have modified the landscape in recent decades, according to new research from the University of East Anglia.
A new study published today shows that population declines have been greatest among species that migrate to areas with more human infrastructure – roads, buildings, power lines, wind turbines – as well as high population densities and prey levels. does.
Habitat degradation and climate change have also played a part in driving the long-term decline.
The research team hopes their work will help them learn how to best target conservation efforts.
Dr James Gilroy from the UEA School of Environmental Sciences said: “We know that migratory birds are in greater decline than non-migratory species, but it is not clear why.
“We wanted to find out where in their life cycle these migratory species are most vulnerable to human impacts.”
The research team identified 16 human-induced threats to migratory birds, including infrastructure associated with bird disturbance and collisions, the conversion of land from natural habitats to human land use, and climate change.
Advances in satellite imagery allowed the team to map each of the 16 threats across Europe, Africa and western Asia. The team also produced the first large-scale map of hunting pressure across the region.
A total of 103 species of migratory birds were studied, including several rapidly declining species such as the tortoise, pigeon and common cuckoo, using the massive dataset.
The team calculated ‘threat scores’ for factors such as habitat loss and climate change, breeding locations as well as non-breeding categories.
They then explored the relationship between these threat scores and bird population trends, calculated from 1985 to 2018 by the Pan-European Common Bird Monitoring Scheme (PECBMS).
Dr C, Lyre Buchan, from the UEA School of Biological Sciences, said: “We found that human modification of landscapes across the bird’s distribution range in Europe, Africa and Western Asia is associated with decreased numbers of more than 100 Afro-Eurasian migratory birds.
“When we talk about landscape modification, we mean things like roads, buildings, power lines, wind turbines – anything that isn’t naturally there.
“One of the biggest impacts is caused by things that would kill a bird outright – for example flying into a wind turbine, a building, being struck by lightning on a power line, hitting a vehicle, or hunting. We found that exposure to these is reflected in population reductions in breeding birds at risk of human-induced ‘direct mortality’ in winter ranges of bird.”
Dr. Aldina Franco from UEA’s School of Environmental Sciences also said: “Our findings are important because we need to understand which species are being most affected by humans in decline in their seasonal migrations. Pointing out that birds are exposed to these Threats are most exposed, we can get help. Target protection work.”
The research was led by the 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 Science and Technology Foundation.