Climate Change and Agriculture Transformations Contribute to Changes in Sweden’s Bird Species
Sweden’s bird species have been experiencing changes due to various factors, including climate change and transformations in the agricultural landscape. According to ornithologist Anders Wirdheim, the leaf warbler, which is primarily a northern species, has been disappearing in warm southern locations. Wirdheim suggests that the warming climate is making it unfavorable for the leaf warbler to thrive, potentially leading to its replacement by the warbler, which is expanding in Sweden.
While climate change is a significant factor in species decline, Wirdheim emphasizes the transformation of the agricultural landscape as the biggest problem. Forestry also poses a threat to bird species. However, Wirdheim predicts that the effects of climate warming will become more noticeable in the decades to come.
Certain bird species have benefited from milder winters and a warmer and drier climate. Winners include the pine warbler, wren, sparrowhawk, and gray warbler, all of which have seen significant increases in the last 20 years. These species are characteristic of Mediterranean countries and thrive in mild climates.
Identifying the losers is more challenging, as many of Sweden’s seagulls have declined, but it is unlikely to be climate-related. The eider, on the other hand, may be experiencing a decline due to rising temperatures affecting the availability of its food source, blue mussels. Danish studies have shown that the mussels produce less fat in warmer temperatures, possibly impacting the eider’s ability to sustain itself before reproduction.
There are also unexpected changes in bird statistics. Traditionally, it was believed that mountain birds would struggle as temperatures rise. However, species like the pied piper, marsh plover, and mountain lab have significantly increased in numbers since the turn of the millennium. Wirdheim suggests that factors other than temperature, such as rainfall or food availability, may be influencing these species’ population growth.
Despite the changes, one certainty is that Sweden’s list of breeding birds will continue to expand over time. Since 2000, only one species (black-legged sandpiper) has disappeared, while six new species have been added, such as cormorant, egret, and black-capped gull. Spoonbills, egrets, and bee-eaters are also expected to arrive soon in Sweden as they spread northward.
Anders Wirdheim expresses mixed emotions regarding the changes. While he appreciates the arrival of beautiful bird species like the bee-eater, he acknowledges the sadness that accompanies the overall shifts. Wirdheim believes that Swedish bird species will likely manage relatively well with climate change but expresses concern for the potential loss of numerous species in other areas, such as the mountain rainforests of the tropics.
The Swedish bird census shows that some species have increased significantly in the last two decades, while others have declined. Winners include the mallard duck, white-tailed eagle, wren, spruce warbler, and gray coot, among others. Losers include the puffin, eider, barn swallow, pine tit, and greenfinch, among others. Several species have remained stable for a long time.
As Sweden’s bird fauna continues to evolve, it reflects the complex interplay of climate change, agricultural transformations, and other ecological factors. While some species thrive in warmer conditions, others face challenges as their habitats and food sources change. The ongoing monitoring and conservation efforts are crucial to understanding these changes and mitigating their potential impacts on bird populations.