2020-12-08
27 May 2015
Butterflies in sharp decline
The diversity of butterflies has changed since 1900. A new study now provides the first inventory underlining the decline of butterflies in Denmark. It shows that twelve species (10% of Danish butterfly species) have gone extinct during the last fifty years. This decline is continuing and a number of species are so critically endangered today that they may become extinct within the next few years.
A significant difference was found between those species that have gone extinct, and those that are still doing relatively well in the Danish countryside. 'The greatest losses have mainly been observed for butterfly species that live in the woods. Out of the twelve species of butterflies that have been lost, ten were native to woodland habitats. The species that have gone extinct in Denmark include attractive and colourful butterflies such as the Cryptic Wood White, Duke of Burgundy Fritillary, and Clouded Apollo,' says Anne Eskildsen, who led the project as part of her PhD thesis at Aarhus University, Denmark. Conditions are hard not only for species with woodland habitats, but also for species that are associated with rare host plants. Generalist species do much better as they can thrive in a number of different habitats.
University of Amsterdam
From decline to collapse
In just 5 Years
from may 2015 to june 2020
June 22, 2020
Danish data show collapse to butterflies
During this year's surveys of butterflies, many naturalists have noticed that there seem to be extremely few butterflies flying. In a forum thread in the Butterfly Atlas´ FB group, frustrated observers have shared their observations, and data confirms the disaster.
Only 8 species has a better score in 2020 than average for the previous 4 years. 52 scores worse. For some species, the lack of observations from 2020 is due to the fact that they have not yet started flying, but for the vast majority, the decline is quite real and frightening. Many of these species have an extremely low dispersal potential, and once gone from a locality, they will never return. This year's decline will therefore lead to a permanently degraded butterfly fauna, where perhaps 20-30% of the rare species' occurrence may have been cut down with one blow.
The reasons for the decline are first and foremost a continuous deterioration of the already limited habitats for the species. But the long drought periods in both 2018, 2019 and 2020 have undoubtedly made it even harder butterfly larva, which feeds on fresh plant material. Combined with a high winter water level at some of the species' localities, it may have contributed to the collapse.
I was too late, I do not think I can help them and it saddens me
I love them and still I can do nothing for them - In my lifetime I went from hope to despair
and now I do not even know how to fix this