Patterns of long-term population trends of three lupine-feeding butterflies in Wisconsin
Published source details
Swengel A.B. & Swengel S.R. (2018) Patterns of long-term population trends of three lupine-feeding butterflies in Wisconsin. Diversity, 10, 31.
Published source details Swengel A.B. & Swengel S.R. (2018) Patterns of long-term population trends of three lupine-feeding butterflies in Wisconsin. Diversity, 10, 31.
This study is summarised as evidence for the following.
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Legally protect habitat
A replicated, site comparison study in 1991–2014 in 40 sites of pine-oak barren in Wisconsin, USA (Swengel and Swengel 2018) found that at sites with the highest level of habitat protection for populations of Karner blue butterflies Lycaeides melissa samuelis, frosted elfin Callophrys irus and Persius duskywing Erynnis persius abundance did not change in central Wisconsin but Karner blue decreased in northwestern Wisconsin, and in central Wisconsin sites with lower levels of protection populations of all species decreased. At sites in central Wisconsin which were specifically managed to protect and enhance Karner blue habitat (“reserves”), Karner blue, frosted elfin and Persius duskywing numbers did not change from 1991–2014, but at timber management sites (“shifting mosaic” sites) and along uncanopied roadsides and powerline rights-of-way (“permanency of habitat” sites) populations decreased (data presented as statistical results). However, in northwestern Wisconsin Karner blue numbers declined in reserves over the period (data presented as statistical results). Sites termed “shifting mosaic” and “permanency of habitat” were managed “with consideration for the Karner blue butterfly and its habitat”, but no further management details are provided. In central Wisconsin, surveys took place in May–June 1991–2014 for frosted elfin and Persius duskywing, and twice during both spring and summer generations of the Karner blue (months not provided) in 10 reserves, 10 shifting mosaic and five permanency of habitat sites. In 1991–2014 in northwestern Wisconsin, surveys took place for the Karner blue only, once a year in their summer generation (month not provided) in 13 reserves, one shifting mosaic and one permanency of habitat sites. There were multiple survey locations/site (numbers not given). Not all sites were surveyed for the whole period or every year. Surveys were of varying lengths and conducted simultaneously along one set of parallel transects (5–10 m apart) in each site.
(Summarised by: Eleanor Bladon)