In their recently published study, the bayklif junior research group MintBio evaluated climatic and land use-related changes in the occurrence of butterflies, grasshoppers and dragonflies in Bavaria over a period of 40 years.
According to these data, occupancy (proportion of sites occupied by a species per year) decreased for 37% of the species studied, increased for 30%, and showed no significant trend for 33%. The greatest declines were found in butterflies and grasshoppers, each with 41% of the species. In contrast, 52% of dragonfly species increased.
Temperature preference and habitat specificity appear to be the most important factors in these trends:
In butterflies, habitat specialists decreased while generalists increased or remained stable. In contrast, for semiaquatic dragonflies, both generalists and specialists increased. These results may indicate a threat in terrestrial habitats, as the occurrence of butterfly specialists in particular depends mainly on habitat quality and area. Both have improved in aquatic habitats in recent decades, but not in terrestrial habitats.
Engelhardt EK, Biber MF, Dolek M, Fartmann T, Hochkirch A, Leidinger J, Löffler F, Pinkert S, Poniatowski D, Voith J, Winterholler M, Zeuss D, Bowler DE, Hof C : Consistent signals of a warming climate in occupancy changes of three insect taxa over 40 years in central Europe.
Global Change Biology 2022, DOI