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Individual study: Restored wetland praire areas provide more resources than unrestored areas for the great copper Lycaena xanthoides in the Willamette Valley, Oregon, USA

Published source details

Severns P.M., Boldt L. & Villegas S. (2006) Conserving a wetland butterfly: quantifying early lifestage survival through seasonal flooding, adult nectar, and habitat preference. Journal of Insect Conservation, 10, 361-370


The great copper Lycaena xanthoides is restricted in Western Orgeon to seasonally flooded prairie wetland areas with small mounds remaining dry throughout the year. This study monitored the butterfly’s behaviour and survival at two sites with restored wetland prairie vegetation, in the Willamette Valley, Oregon, USA.

The study was carried out at three sites with small populations of the great copper, 1.5 km apart. Two sites - Tsal-uk-wah and Pacific – had areas planted with native wetland prairie plants in the late 1990s.

Cover by grasses, herbaceous plants, bare ground (used for basking) and the nectar plant Puget Sound gumweed Grindelia integrifolia, was measured in five 5 m2 quadrats, in 50 x 20 m plots within and just outside the restored areas. The larval food plant willow dock Rumex salicifolius was too sparsely distributed to be counted in the quadrats.

Adult great coppers were caught and marked at each site for one hour in the morning every three to four days between 5 July and 7 August 2005. Between 14 and 18 were marked at each site in total. Marked butterflies were searched for between 10:00 h and 16:00 h on each survey day. Adults visiting flowers for nectar were recorded.
Great copper eggs found on 24 willow dock plants across all sites were observed from late summer 2004 until they became third instar larvae in June 2005. Whether the plants were flooded or remained dry during the wet season was recorded.

Restored plots had significantly higher bare ground cover (average 16 and 34% at Tsal-uk-wah and Pacific respectively) and G. integrifolia cover (average 55 and 21%) than adjacent unrestored areas (<0.2% cover of bare ground and G. integrifolia at both sites).

88% of great copper nectar visits observed during the study were to G. integrifolia.
The same day recapture rate was higher on the two sites with restored areas (83% and 79% at Tsal-uk-wah and Pacific respectively) than on the unrestored site (19%). There was no difference between the three sites in the long-term recapture rate (butterflies recaptured on the same site on subsequent days).
Seven of 46 eggs (15%) on plants that were not flooded survived, compared to two of 84 eggs (2%) laid on plants that were inundated. This implies that dry mounds are important for the great copper in this habitat.
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