Ecological studies on the large copper butterfly Lycaena dispar (Haw.) batavus (Obth.) at Woodwalton Fen National Nature Reserve, Huntingdonshire

Published source details Duffey E. (1968) Ecological studies on the large copper butterfly Lycaena dispar (Haw.) batavus (Obth.) at Woodwalton Fen National Nature Reserve, Huntingdonshire. Journal of Applied Ecology, 5, 69-96.
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This study is summarised as evidence for the following.

	Action	Category
	Translocate to re-establish populations in known or believed former range Action Link
	Remove, control or exclude native predators Action Link
	Rear declining species in captivity Action Link
	Release captive-bred individuals to the wild Action Link

Translocate to re-establish populations in known or believed former range

A review from 1909–1964 in fens in Cambridgeshire and Norfolk, UK, and Tipperary, Ireland (Duffey 1968) reported that five translocated populations of large copper Lycaena dispar survived for up to 38 years, but ultimately died out or required additional releases to survive. Three populations of Lycaena dispar rutilus released as adults and/or caterpillars survived for zero, 23 and two years. One population of Lycaena dispar batavus survived for 38 years, but was supplemented by additional releases of captive-bred individuals, and ‘wild’ caterpillars were regularly reared in cages. Another L. d. batavus population died out 13 years after release. In 1909, L. d. rutilus caterpillars (number not given) were released at Wicken Fen, Cambridgeshire. In May 1913, following planting of great water dock Rumex hydrolapathum on a bog in Greenfields, Tipperary, 120 L. d. rutilus caterpillars from Germany were released. The following year, 400 adults raised from 700 caterpillars collected in Germany were released at the same site. In 1926, a total of 550 pupae from Tipperary were placed in cages in Woodbastwick Marshes, Norfolk, and the adults released as they emerged. In 1926, an 8.8-ha area of Woodwalton Fen, Cambridgeshire, was cleared of bushes and great water dock was planted. In 1927, thirteen female and 25 male L. d. batavus from the Netherlands were released at the site. This population was supplemented with captive-bred caterpillars or adults when numbers were low, and from the 1930s, ‘wild’ caterpillars were routinely reared in muslin cages to protect them from predation. In 1942, L. d. batavus (number not given) from Woodwalton were released in Tipperary.

(Summarised by: Andrew Bladon)
Remove, control or exclude native predators

A replicated, paired, controlled study in 1964–1965 in a fen in Cambridgeshire, UK (Duffey 1968) reported that excluding native predators increased the survival of large copper Lycaena dispar batavus caterpillars. Results were not tested for statistical significance. On plants which were caged to exclude birds and mammals, the survival of large copper caterpillars was 73% (79/108 survived), compared to 4% (11/300 survived) on plants without cages. Data from four caged plants were excluded as the caterpillars abandoned them after eating all of the leaves. The author reported that on plants kept in cages which excluded birds, mammals and parasitic insects, 297/354 (84%) caterpillars survived. Four batches of 20 great water dock Rumex hydrolapathum plants were selected. In each batch, four plants were >100 cm tall, and 16 were 50 cm high. In May 1964, three or 12 large copper caterpillars were placed onto each plant, and half of the plants in each batch were covered with a 6-mm plastic mesh cage to exclude birds and mammals. In July 1964, all surviving caterpillars and pupae were counted. In 1965, a total of 354 caterpillars were reared in six muslin cages to exclude birds, mammals and parasitic insects (no further details provided).

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

A replicated, paired, controlled study in 1964 in a fen in Cambridgeshire, UK (Duffey 1968) reported that semi-wild large copper Lycaena dispar batavus caterpillars reared at high density on small great water dock Rumex hydrolapathum plants had lower survival than caterpillars reared at lower density or on larger plants. Results were not tested for statistical significance. On small plants, the survival of large copper caterpillars reared in groups of 12/plant was 35% (67/192 survived), compared to 65% (31/48 survived) for caterpillars in groups of three/plant. However, on large plants the survival of caterpillars in groups of 12/plant was 81% (39/48 survived) compared to 75% (9/12 survived) for caterpillars in groups of three/plant. The author reported that small plants with 12 caterpillars/plant were abandoned after all the leaves had been eaten, before the caterpillars were fully grown. In a fen with a semi-wild large copper colony, four batches of 10 great water dock plants were selected. In each batch, eight plants were 50 cm tall (3 leaves/plant) and two were >100 cm high (9–20 leaves/plant). In May 1964, three or 12 large copper caterpillars were placed onto each plant, and the plants were covered with a 6-mm plastic mesh cage to exclude birds and mammals. In July 1964, all surviving caterpillars and pupae were counted.

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

A review in 1929–1966 in three fens in Cambridgeshire and Norfolk, UK (Duffey 1968) reported that released large copper Lycaena dispar batavus caterpillars had lower survival rates than captive caterpillars, and three released populations ultimately died out or required additional releases to survive. Results were not tested for statistical significance. One population of captive-bred large copper survived for 12 years after release, until the fen was drained, but a second population died out two years after release. A third population was maintained for over 30 years by continued releases. In this population, survival from the egg stage to caterpillars in spring in the released population was 4.4%, compared to 5.1% in the captive population, but the survival of caterpillars from spring to pupation was 15.1% in the released population, compared to 79.1% in the captive population. In winter 1929–1930, a 3-ha fen in Cambridgeshire was cleared and planted with great water dock Rumex hydrolapathum. In May 1930, ‘a sufficient number’ of large copper caterpillars were placed on marked plants, and a second release was conducted in 1931 or 1932. In 1942 the fen was drained. In June–July 1949, eighty adults were released on a fen in Norfolk. From the 1930s–1966, a semi-wild population was maintained at a second Cambridgeshire fen, by regular (becoming annual) releases of captive-bred caterpillars. From 1961–1966, the survival of released and captive caterpillars was estimated each year.

(Summarised by: Andrew Bladon)