Scientists in Sweden and the Netherlands are teaching migrating birds to fly further north in order to counter the impact of climate change
The idea of helping migratory birds on their epic journeys is not a new one. You might have seen the 2019 French film, Spread Your Wings (Donne moi des ailes) which was based on the true-life story of scientist, Christian Moullec and his son who hand reared a group of rare geese and then, using microlights, guided the geese along their migration routes.
Now, scientists in Sweden and the Netherlands are turning their hand to helping migratory birds, by changing their migration routes. Why? Well, the answer is all to do with climate change. With spring in the Netherlands arriving earlier than it used too so caterpillars are hatching out earlier and then pupating earlier. Year-round resident birds were aware of this change and appear to be adapting accordingly. However, for migratory birds such as the pied flycatcher, who are reliant on the easy availability of caterpillars to feed their young with, this was a problem. Spending their winters in West Africa meant that these tiny birds were seemingly unaware of the earlier arrival of the European spring and they were arriving at their breeding grounds in the Netherlands at the same time that they always have, only to find out that the caterpillars were pupating before their chicks had time to fledge. The result was that more and more chicks were starving to death and in some parts of the Netherlands the population of pied flycatchers has crashed 90 per cent over the past twenty years.
When the birds arrived in the Netherlands all primed up and ready to breed a team of Swedish and Dutch scientists caught a group of them and then drove nearly 600km north (a distance the birds could cover on their own in two days) with them to Skåne in southern Sweden where the birds were then released in a suitable habitat. Being that much further north meant that spring was only just arriving here and the flycatchers were then able to profit from a bonanza of caterpillars and had a significantly more successful breeding season than those birds who remained behind in the Netherlands.
The key question though was what would happen in the following years when the birds flew from Africa back to Europe again? After several years of observation, the team of scientists have announced in the journal Nature Ecology & Evolution that those birds that had been raised in Sweden didn’t stop at all in Holland but continued flying north to arrive again to a caterpillar feast in Sweden.
One of the scientists involved in the experiment, Jan-Åke Nilsson, an ecologist at Sweden’s Lund University, said, “The birds that were given a lift from the Netherlands to Skåne synchronized very well with the food peak. As they started to breed about 10 days earlier [than] the Swedish pied flycatchers they had a dramatically better breeding success than the Swedish ones as well as a better success than the pied flycatchers that remained in the Netherlands”.
Scientists involved in the experiment now believe that if some populations of migratory birds could be trained to fly a little further north that they’d be able to overcome some of the negative impacts of climate change. As Nilsson says, “By flying a little further north, these birds, at least in principle, could synchronize with their food resources, and there is hope that robust populations of small birds can be maintained”.
