The re-establishment of the large copper butterfly Lycaena dispar batava obth. on Woodwalton Fen National Nature Reserve, Cambridgeshire, England, 1969-73

Published source details Duffey E. (1977) The re-establishment of the large copper butterfly Lycaena dispar batava obth. on Woodwalton Fen National Nature Reserve, Cambridgeshire, England, 1969-73. Biological Conservation, 12, 143-158.
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This study is summarised as evidence for the following.

	Action	Category
	Employ areas of semi-natural habitat for rough grazing (includes salt marsh, lowland heath, bog, fen) Action Link
	Rear declining species in captivity Action Link
	Release captive-bred individuals to the wild Action Link

Employ areas of semi-natural habitat for rough grazing (includes salt marsh, lowland heath, bog, fen)

A controlled, before-and-after study in 1971–1973 in a fen in Cambridgeshire, UK (Duffey 1977) reported that after grazing by cattle, large copper butterflies Lycaena dispar batava laid more eggs/plant than either before grazing or than in ungrazed fens. Results were not tested for statistical significance. In the first two years after grazing commenced, the number of eggs (2.1–3.1 eggs/plant) was higher than in either the year before grazing on the same fen (0.1 eggs/plant) or in two ungrazed fens (0.1–1.7 eggs/plant). From late May–early August 1972–1973, one 4.2-ha fen was grazed by six bulls for 9 weeks/year, while two adjacent fens (2.3–3.3 ha) were not grazed. In summer 1972, a total of 137 male and 65 female adult butterflies were released from two cages, one in each ungrazed fen, to supplement the local population. In summer 1973, another 93 males and 70 females were released in one of the ungrazed fens. In August 1972, the vegetation height in the grazed fen (0.6–1.0 m) was lower than in the ungrazed fens (1.2–2.0 m). In the first week of August 1971–1973, all great water dock Rumex hydrolapathum plants in each site were examined, and the number of eggs counted.

(Summarised by: Andrew Bladon)
Rear declining species in captivity

A controlled study in 1968 at a research station in Cambridgeshire, UK (Duffey 1977) reported that large copper butterflies Lycaena dispar batava laid more eggs in a cage kept in a greenhouse than in a cage kept outside, and eggs in the greenhouse had a higher hatching success. Results were not tested for statistical significance. The number of eggs laid in a cage kept in a greenhouse (498 eggs) was higher than the number laid in a cage kept outside (126 eggs). In addition, the proportion of eggs which hatched was higher in the greenhouse (91%) than outside (40%). In summer 1968, two cages (5.40 × 1.65 × 1.80 m) were constructed from 1 × 1 cm mesh. One was kept in a greenhouse and the other was placed outside. Each cage contained 15 female and 23 male large coppers, and 20 potted great water dock Rumex hydrolapathum plants. From 17 May–14 August 1968, the mean maximum temperature in the greenhouse cage (23.8°C) was higher than in the outside cage (16.8°C), but the mean minimum temperature was similar (greenhouse: 8.7°C; outside: 8.6°C). Eggs were counted daily.

(Summarised by: Andrew Bladon)
Release captive-bred individuals to the wild

A study in 1970–1976 in a fen in Cambridgeshire, UK (Duffey 1977) reported that after the release of captive-bred large copper butterflies Lycaena dispar batava, the number of eggs laid/female and the number of caterpillars emerging after hibernation increased over three years, and the population survived for at least six years. Results were not tested for statistical significance. One year after the first release of adult butterflies, 111 caterpillars emerged from hibernation. In the second year, 427 caterpillars emerged, and in the third year 1,344 caterpillars emerged. The number of eggs laid/female increased from 4.85 in the first year to 89–100 in the fourth year. Six years after the first release, eggs were widely distributed across the site. In late summer 1970, caterpillars and pupae from two captive-bred populations were placed in muslin cages across a fenland nature reserve, from which 517 males and 551 females were released. In spring 1971–1973, wild-hatched caterpillars were collected and reared to pupation in muslin cages, and additional releases from captive stock were made (344–554 males/year, 208–446 females/year). Wild-hatched caterpillars were reared in cages again in later years. No details are given on how the eggs and caterpillars were counted and collected.

(Summarised by: Andrew Bladon)