The war in Ukraine caused endangered eagles to change their usual flight plans, reveals new research.
Greater Spotted Eagles altered their regular course when migrating through the country during Russia's 2022 invasion, according to the study led by British scientists.
The species is classified as "vulnerable" by the International Union for Conservation of Nature (IUCN).
Researchers from the University of East Anglia (UEA), the British Trust for Ornithology (BTO) and the Estonian University of Life Sciences compared the movement and migration of the Greater Spotted Eagle through Ukraine, before and shortly after it was invaded by Russia in February 2022.
The team was already studying the species when the war began, with the dangers faced by migratory birds usually related to disruptive weather or drought, changes in land use affecting traditional stopping-off points, or destruction of essential habitats.
But during the Russian invasion, researchers found that the eagles, which had previously been fitted with GPS tracking devices, were exposed to artillery fire, jets, tanks and other weaponry - as well as unprecedented numbers of soldiers moving through the landscape and millions of displaced civilians - during their journey.
Study lead author Charlie Russell, a UEA PhD student, said: “We did not expect to be following these birds as they migrated through an active conflict zone.
"Armed conflicts can have wide-ranging impacts on the environment, including changes in animal behavior.
“Our study provides the first quantitative evidence of this, showing how migrating eagles made deviations to avoid conflict events and spent less time refueling at stopover sites.
"It also indicates that there are potentially many human activities, beyond wars, that likely change or impact animal behavior.”
The eagles' migration pattern in March and April 2022, gathered from the tracking data, was compared to previous years as they passed between wintering areas in southern Europe and East Africa and key breeding grounds in southern Belarus.
The findings, published in the journal Current Biology, show that the eagles made "large deviations" from their traditional migratory routes.
They also spent less time stopping at their usual "refueling" sites in Ukraine or avoided them entirely.
The changes resulted in the eagles traveling further and arriving on their nesting grounds later than usual.
Scientists say that could seriously affect them and likely contributed to reduced physical fitness at a time when peak conditions are critical to successful breeding.
Russell added: “The war in Ukraine has had a devastating impact on people and the environment.
"Our findings provide a rare window into how conflicts affect wildlife, improving our understanding of the potential impacts of exposure to such events or other extreme human activities that are difficult to predict or monitor.
“These types of disturbances can have significant impacts on the behavior, and potential fitness of the eagles.
"For individuals breeding in these areas, or other species that are less able to respond to disturbance, the impacts are likely to be much greater."
Dr. Adham Ashton-Butt, BTO's senior research ecologist, said: “Our findings show how human disturbance can inadvertently impact wildlife.
“Migratory birds such as Greater Spotted Eagles are drastically declining all over the world and it’s imperative that we better understand and mitigate our effects on these charismatic species.
“Similar responses have been recorded for birds residing in military training zones, but these new findings that show an impact for migratory species means that disturbance events can have more far-reaching impacts across many more individuals, over greater distances.
“The size of the effect on migratory behavior was also quite large, substantial enough to be detected in a relatively small sample size.”
By early March 2022, when the first of 19 GPS-tagged eagles entered Ukraine on their way north, the war had spread to most of the country's major cities.
The researchers found that the birds flew further and less directly to breeding grounds, traveling an extra 85 kilometers (53 miles) on average.
Migrations also took 246 hours compared to 193 hours pre-conflict for females, and 181 hours compared to 125 hours pre-conflict for males.
Males also traveled more slowly than in the years before the war.
Just six out of 19 of the eagles made stopovers in Ukraine, compared to 18 out of 20 in 2018-2021, while some important stopover sites, for example in Ukrainian Polesia, were not used at all in 2022.
Co-author Dr. Aldina Franco, of UEA, said: “Remote tracking of wildlife enables researchers to understand the impact of human activities, such as hunting or energy infrastructure, on the environment and wildlife populations.
"In this case, it is providing insights on how armed conflict events impact animal behavior and migration."
She added: “Collecting this data is limited by the logistical implications of working in these areas and previous research has been limited to resident birds in military training zones.
"However, our tracking data gives us a unique window into how migrating eagles experience and respond to intense conflict.”
