migratory birds return earlier at the end of winter in northern Europe

Migratory birds arrive in France five to six days earlier than in the 1980s. With the mild temperatures, they are tempted to return to northern Europe earlier and earlier for the breeding period.

Early flights of migratory birds heading towards northern Europe have been observed since the beginning of February. Mildness, temperatures and global warming are changing the rhythm of these birds as the end of winter approaches. “I have never seen that”, confides an ornithologist from the Gers cited by La Dépêche du Midi (paid item). Since the end of January, he has observed flights of common cranes over his department. Movements of storks and woodcocks have also been observed elsewhere. These birds cross France from southern Europe or Africa to go north for nesting. With the mild temperatures, remember that France experienced its hottest half of February this year since 1930, and with global warming, they are more tempted to return to the north earlier and earlier at the end of winter to the reproductive period. This is not new this year, the phenomenon is documented. Migratory birds arrive in France five to six days earlier than in the 1980s, indicates the French office for biodiversity, this average concerns around fifteen species.

Impacts on the life cycle

This early migration, a worrying illustration of global warming, can become a problem for birds. If they really come back too early, when winter is not over, underlines Benoît Fontaine, conservation biologist at the national museum of natural history. Until now, the natural cycle means that the laying period and the birth of chicks coincide, in spring, with a peak in the abundance of insects and plants in nature, which makes it possible to feed them. If too large a gap appears, adaptation can be complicated for certain species. However, explains this specialist, the greatest threat to the survival of birds in the years to come is not so much the rise in temperatures, but changes in the agricultural environment.

Intensive agriculture is the main cause of the decline of birds in Europe. A fact highlighted in 2023 in the largest study ever carried out on the subject. Some 28 countries contributed to study 170 different bird species. The results of this work, involving the CNRS in particular, have shown that more than global warming, more than the loss of forest area, it is intensive agriculture which has the greatest impact on bird mortality. Fertilizers and pesticides have in fact modified their food chain and reduced insect populations. If we add urbanization and rising temperatures. Researchers have calculated that 20 million birds have been disappearing in Europe from one year to the next for almost 40 years.