Vienna – A new study from the University of Veterinary Medicine Vienna (Vetmeduni) reveals that migratory birds remain physiologically resilient even after long and potentially strenuous flights across the Mediterranean Sea, regardless of weather conditions. The findings suggest that these birds are impressively adapted to cope with the challenges of migration, including unpredictable environmental factors.
Researchers from the Konrad Lorenz Institute of Comparative Ethology (KLIVV) at Vetmeduni studied two species – the Garden Warbler (Sylvia borin) and the Whitethroat (Curruca communis) – on the island of Ponza, Italy, during their spring migration. They measured levels of the stress hormone corticosterone (CORT) in the birds’ blood and found no significant differences between calm and adverse weather conditions.
“It is fascinating to see how well these small birds are prepared for their journey,” said lead author Erica Calabretta. “Even under headwinds or lower temperatures, their stress levels remained unchanged.”
The study found that successful migrants had good fat reserves and overall excellent physical condition. Birds appear to time their departure and manage their energy reserves strategically. “These birds are true masters of planning,” explained Prof. Leonida Fusani, senior author and head of KLIVV. “They optimize their travel timing and are selective in the conditions under which they fly.”
However, the research only covers birds that successfully completed the crossing. “We still need to study what happens to those that don’t make it,” Calabretta added. With climate change causing increasingly extreme weather events in the Mediterranean, this research has important implications for conservation. “Unpredictable conditions could deplete their energy and increase vulnerability to predators,” noted KLIVV researcher Dr. Ivan Maggini.
The full study, titled “Passerine stopover physiology: weather variability does not alter corticosterone dynamics after sea crossing”, was published in the Journal of Avian Biology.
Source: University of Veterinary Medicine Vienna
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