Birds changing flight habits - 15th November 2021

Birds which normally migrate to sunnier places are now spending longer in Europe, raising questions about whether some will stop winter migration completely, scientists have reported.

A study by Durham University found a number of birds which generally cross the Sahara are spending up to 60 days per year more in European breeding grounds than before. This may be due to climate change.

Scientists studied 50 years of data from The Gambia and Gibraltar.

The study, published in the journal Global Change Biology, used the data to examine changes in arrival and departure dates over the period. It had previously been thought that birds timed migration based on day length. However, a university spokesman said the study's findings suggest that birds are also making more sophisticated decisions, responding to factors such as "changes in climate and available vegetation".

Lead author Kieran Lawrence, from the department of biosciences commented: "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." He explained that the changes could result in longer breeding seasons for these species. This could impact other species, both in Europe and in the traditional winter destinations.

The behavioural changes could also create increased competition for food in Europe in autumn and winter.

At the same time, in Africa, there would be a dramatic effect on ecosystems, since birds play a key role in controlling the number of insects, in spreading seeds and pollinating plants.

Professor Stephen Willis, head of the project, said his team will now develop a model to present a range of possible future outcomes of bird migration.