Silver-Washed Fritillary spreads northwards with warming climate

Last summer saw fewer butterflies in the Finnish landscape than for a decade

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Butterflies in Finland have moved their range margins northwards on average by some 60 kilometres, with maximum shifts of over 300 kilometres for three species in ten years.
      These three species are the Silver-Washed Fritillary (Argynnis paphia), the Holly Blue (Celastrina argiolus), and the Black-Veined White (Aporia crataegi).
     
The information is based on a study conducted by the Finnish Environment Institute (SYKE) in cooperation with the South Karelia Allergy and Environment Institute. The geographical distribution of butterflies was compared between two periods, 1992-1996 and 2000-2004.
      For example the Silver-Washed Fritillary has spread from the southern coast and Southwestern Finland northwards to the latitude of Kuusamo and even Rovaniemi.
      Butterflies that live at the edges of forests, feed on woody plants during the larval phase, and are more mobile, have also spread northwards more quickly.
     
The study indicates that the spreading of butterfly species northwards is attributable to the fact that common and widespread trees and shrubs are also migrating northwards as a consequence of climate change.
      The Poplar Admiral (Limenitis populi), the Holly Blue, and the Black-Veined White are all likely to spread northwards as the warming of our climate proceeds.
      Species that live in meadows have not spread as quickly as the species found on forest edges.
     
Because of the declining availability of habitats, including meadows, many species, such as the Clouded Apollo (Parnassius mnemosyne), the Large Grizzled Skipper (Pyrgus alveus), and the Green-Underside Blue (Glaucopsyche alexis) can be expected to be less able to migrate northwards to climatically more favourable areas.
     
Last summer was a poor time for butterflies. The number of butterflies flying in the rainy and cold weather was the lowest for a decade, indicates a recent report of the National Butterfly Recording Scheme (NAFI) in Finland.
      The information was gathered from a total of 220 municipalities, involving around 150,000 butterfly species. The same number was also counted in the equally rainy summer of 1998.
      At the last count a couple of years ago, the number was twice as high.


Links:
  Silver-washed fritillary (Wikipedia)
  Finnish Environment Institute (SYKE): Butterflies in Finland spread northwards with warming climate
  South Karelia Allergy and Environment Institute: Monitoring the Finnish butterflies

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