Birds changing flight habits - 15th November 2021

Migratory birds are currently extending the time they spend in Europe, raising the possibility that winter migration may eventually cease altogether, according to scientists.

A team of experts at Durham University, in the UK, have been conducting research into changing patterns in flight behaviour by migrating birds. Their study reveals that a number of trans-Saharan birds are remaining in European breeding grounds by as much as an additional 60 days annually. It's thought this may be down to climate change.

Scientists were able to exploit 50 years of data from The Gambia and Gibraltar, collated by ornithologists, and established that the birds affected included nightingales, willow warblers and several wagtails. The paper, which was published in the journal Global Change Biology, explored modifications in the timings of the birds' flights between their seasonal habitats across five decades.

Although it had been assumed that the arrival and departure schedules of these migratory species were linked to day-length, a university spokesman announced that the findings infer the birds are also "making nuanced decisions". These are apparently influenced by key elements such as "changes in climate and available vegetation".

Kieran Lawrence, lead author of the study, based in the University's biosciences department added:

"If the trends we have seen in this study continue, we may see that, in time, some birds will spend no time at all in sub-Saharan Africa, and instead spend the full year within Europe. The changes in migratory habits we are already seeing could lead to longer breeding seasons for these species, as well as knock-on effects on other species, both here in the UK and in the traditional winter migration destinations."

He also observed that should these birds refrain from migrating, then competition over limited food sources in Europe would intensify over the colder months.

Meanwhile, the loss of the birds in Africa would have "ecosystem implications" around insect consumption, seed dispersal, and pollination.

Professor Stephen Willis, the project lead, explained his team will now generate a new model intended to simulate migrations and future scenarios.