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WallisDeVries, M., C. A. M. Swaay, et al. (2012). "Changes in nectar
supply: A possible cause of widespread butterfly decline."
<u>Current Zoology</u> <b>58</b>(3): 384-391.<br><br>
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<dd><x-tab> </x-tab>Recent
studies have documented declining trends of various groups of
flower-visiting insects, even common butterfly species. Causes of these
declines are still unclear but the loss of habitat quality across the
wider countryside is thought to be a major factor. Nectar supply
constitutes one of the main resources determining habitat quality. Yet,
data on changes in nectar abundance are lacking. In this study, we
provide the first analysis of changes in floral nectar abundance on a
national scale and link these data to trends in butterfly species
richness and abundance. We used transect data from the Dutch Butterfly
Monitoring Scheme to compare two time periods: 1994-1995 and 2007-2008.
The results show that butterfly decline can indeed be linked to a
substantial decline in overall flower abundance and specific nectar
plants, such as thistles. The decline is as severe in reported flower
generalists as in flower specialists. We suggest that eutrophication is a
main cause of the decline of nectar sources.<br><br>
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