Co-occurrence of prairie and barrens butterflies: Applications to ecosystem conservation

Published source details Swengel A.B. & Swengel S.R. (1997) Co-occurrence of prairie and barrens butterflies: Applications to ecosystem conservation. Journal of Insect Conservation, 1, 131-144.
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This study is summarised as evidence for the following.

	Action	Category
	Manage heathland by cutting Action Link
	Use rotational burning Action Link
	Manage land under power lines for butterflies and moths Action Link
	Cease mowing on grassland to allow early succession Action Link
	Maintain species-rich, semi-natural grassland Action Link
	Cease grazing on grassland to allow early succession Action Link

Manage heathland by cutting

A before-and-after study in 1988–1996 on a pine barren in Wisconsin, USA (Swengel & Swengel 1997) found that the abundance of five butterfly species did not change following the initiation of unintensive cutting instead of burning management. In the first three years after cutting commenced, the abundance of frosted elfin Callophrys irus (1.3 individuals/hour), Olympia marble Euchloe olympia (18 individuals/hour), Karner blue Lycaeides melissa samuelis (120 individuals/hour), Persius duskywing Erynnis persius (1.8 individuals/hour), and dusted skipper Atrytonopsis hianna (1 individual/hour) were all similar to under the previous burning regime (frosted elfin: 0; Olympia marble: 6; Karner blue: 135; Persius duskywing: 0.7; dusted skipper: 0 individuals/hour). In April 1988 and 1991, an area of pine barren was burned. In April 1994, the area was not burned, and unintensive cutting management commenced. Between 1988–1996, butterflies were surveyed along a transect at the site multiple times/year (no further details provided).

(Summarised by: Andrew Bladon)
Use rotational burning

A replicated, site comparison study in 1988–1996 on 17 upland prairies in Missouri, Minnesota, North Dakota and Wisconsin, USA (Swengel & Swengel 1997, same experimental set-up as Swengel 1998 and Swengel & Swengel 2001) found that prairies managed by rotational burning had a lower abundance of six out of seven specialist butterfly species than prairies managed by haying or grazing, or unmanaged areas. Of seven prairie specialist butterfly species, three (gray copper Lycaena dione, regal fritillary Speyeria idalia, arogos skipper Atrytone arogos) were less abundant in rotationally burned areas than in unmanaged areas, and four were less abundant in burned areas than in hayed (regal fritillary, Pawnee skipper Hesperia leonardus pawnee, Dakota skipper Hesperia dacotae) or grazed (Gorgone checkerspot Chlosyne gorgone) prairies. Poweshiek skipperling Oarisma poweshiek abundance in burned prairies was not significantly different from in hayed, grazed or unmanaged areas. See paper for individual species data. Across 17 prairies (16 to >120 ha), eight areas were managed by burning on rotation, six by haying (often in rotation), three by burning and haying, two by grazing, and two were unmanaged. From 1988–1996, butterflies were surveyed on transects through different management areas at each site. Sites were not surveyed in every year.

(Summarised by: Andrew Bladon)
Manage land under power lines for butterflies and moths

A site comparison study in 1988–1996 along two power line rights-of-way in Wisconsin, USA (Swengel & Swengel 1997) found that one out of seven butterflies was more abundant on a right-of-way managed by mowing than on a right-of-way managed by cutting. Frosted elfin Callophrys irus were more abundant along a mown power line right-of-way (4 individuals/hour) than on a right-of-way managed by unintensive cutting (0 individuals/hour). Six other species (Olympia marble Euchloe olympia, Karner blue Lycaeides melissa samuelis, gorgone checkerspot Chlosyne gorgone, Persius duskywing Erynnis persius, Leonard’s skipper Hesperia leonardus leonardus, dusted skipper Atrytonopsis hianna) had a similar abundance on the mown and cut right-of-way (see paper for details). One power line right-of-way through pine barrens was managed by mowing, and a second was managed by unintensive cutting. Between 1988–1996, butterflies were surveyed on transects at each site, but not in every year.

(Summarised by: Andrew Bladon)
Cease mowing on grassland to allow early succession

A replicated, site comparison study in 1988–1996 in 17 upland prairies in Missouri, Minnesota, North Dakota and Wisconsin, USA (Swengel & Swengel 1997, same experimental set-up as 5) found that abandoned prairies had a higher abundance of four specialist butterfly species , but a lower abundance of three species, than prairies managed by haying, grazing or burning. Of seven prairie specialist butterfly species, four (gray copper Lycaena dione, regal fritillary Speyeria idalia, arogos skipper Atrytone arogos, Poweshiek skipperling Oarisma poweshiek) were more abundant in abandoned, unmanaged areas than in prairies managed by grazing, hayed or burning in at least one of three regions. However, three species were less abundant in abandoned prairies than in hayed (Pawnee skipper Hesperia leonardus pawnee, Dakota skipper Hesperia dacotae) or grazed (Gorgone checkerspot Chlosyne gorgone) prairies. See paper for individual species data. Across 17 prairies (16 to >120 ha), two areas were unmanaged for a long time (abandoned), while six areas were managed by haying (often in rotation), eight by burning on rotation, three by burning and haying, and two by grazing. From 1988–1996, butterflies were surveyed on transects through different management areas at each site. Sites were not surveyed in every year.

(Summarised by: Andrew Bladon)
Maintain species-rich, semi-natural grassland

A replicated, site comparison study in 1988–1996 in 17 upland prairies in Missouri, Minnesota, North Dakota and Wisconsin, USA (Swengel & Swengel 1997, same experimental set-up as Swengel 1998 and Swengel & Swengel 2001) found that prairies managed by haying or grazing had a higher abundance of four specialist butterfly species, but a lower abundance of three species than prairies managed by burning or unmanaged sites. Of seven prairie specialist butterfly species, three (regal fritillary Speyeria idalia, Pawnee skipper Hesperia leonardus pawnee, Dakota skipper Hesperia dacotae) were more abundant in prairies managed by haying than in rotationally burned, grazed or unmanaged prairies in at least one of three regions. Gorgone checkerspot Chlosyne gorgone was more abundant in grazed prairies than burned or unmanaged areas. However, three species (gray copper Lycaena dione, arogos skipper Atrytone arogos, Poweshiek skipperling Oarisma poweshiek) were less abundant in hayed or grazed prairies than in unmanaged prairies in at least one of three regions. See paper for individual species data. Across 17 prairies (16 to >120 ha), two areas were managed by grazing, six by haying (often in rotation), eight by burning on rotation, three by burning and haying, and two were unmanaged. From 1988–1996, butterflies were surveyed on transects through different management areas at each site. Sites were not surveyed in every year.

(Summarised by: Andrew Bladon)
Cease grazing on grassland to allow early succession

A replicated, site comparison study in 1988–1996 in 17 upland prairies in Missouri, Minnesota, North Dakota and Wisconsin, USA (Swengel & Swengel 1997, same experimental set-up as 6 and 8) found that abandoned prairies had a higher abundance of four specialist butterfly species, but a lower abundance of three species than prairies managed by grazing, haying or burning. Of seven prairie specialist butterfly species, four (gray copper Lycaena dione, regal fritillary Speyeria idalia, arogos skipper Atrytone arogos, Poweshiek skipperling Oarisma poweshiek) were more abundant in abandoned, unmanaged areas than in prairies managed by grazing, hayed or burning in at least one of three regions. However, three species were less abundant in abandoned prairies than in grazed (Gorgone checkerspot Chlosyne gorgone) or hayed (Pawnee skipper Hesperia leonardus pawnee, Dakota skipper Hesperia dacotae) prairies. See paper for individual species data. Across 17 prairies (16 to >120 ha), two areas were unmanaged for a long time (abandoned), while two areas were managed by grazing, six by haying (often in rotation), eight by burning on rotation, and three by burning and haying. From 1988–1996, butterflies were surveyed on transects through different management areas at each site. Sites were not surveyed in every year.

(Summarised by: Andrew Bladon)