Delayed population explosion of an introduced butterfly

Published source details Boggs C.L., Holdren C.E., Kulahci I.G., Bonebrake T.C., Inouye B.D., Fay J.P., McMillan A.N.N., Williams E.H. & Ehrlich P.R. (2006) Delayed population explosion of an introduced butterfly. Journal of Animal Ecology, 75, 466-475.
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This study is summarised as evidence for the following.

	Action	Category
	Translocate to establish populations outside of known range Action Link
	Release captive-bred individuals to the wild Action Link

Translocate to establish populations outside of known range

A study in 1977–2005 in an alpine meadow in Colorado, USA (Boggs et al. 2006, same experimental set up as Holdren & Ehrlich 1981) reported that a translocated and captive-bred population of Gillette's checkerspot Euphydryas gillettii released outside the species’ native range survived for 28 years, but only increased in size and colonized new sites after 22–25 years. For 21 years after the release of 83 egg clusters, the population size fluctuated between 24 and 143 adults, and remained confined to the release site. However, four years later, the population was estimated at >3,000 adults, and covered 70.4 ha. After a further three years, the population had declined to 150 adults at the release site, but two other habitat patches (0.3 and 0.6 ha) remained occupied (13–153 adults/ha). In July 1977, eggs and adult females were collected in Wyoming, and kept in a laboratory where more eggs were laid. In July–August 1977, eighty-three wild- and captive-laid egg and caterpillar clusters (~10,000 individuals from ~40 females) were released on to bearberry honeysuckle Lonicera involucrata in a 2.25-ha meadow. Details of the translocation taken from Holdren & Ehrlich (1981). In June–July 1978–1989 and 2002–2005, adult butterflies at the release site were caught and uniquely marked every 1–7 days. Recapture rates of marked butterflies were used to estimate the population size in years with sufficient data (1981–1986, 2002–2005). In 1978–1989, 2002 and 2004–2005, egg clusters and/or caterpillar webs were counted throughout the season at the release site, and in 2003–2005 at two newly colonized sites. The relationship between number of egg clusters and adult population was used to estimate the population size in the remaining years. From 1978–1987, areas surrounding the release site were searched for egg clusters or caterpillar webs, and from 2002–2005 a larger area was searched for adults.

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

A study in 1977–2005 in an alpine meadow in Colorado, USA (Boggs et al. 2006) reported that a captive-bred and translocated population of Gillette's checkerspot Euphydryas gillettii released outside the species’ native range survived for 28 years, but only increased in size and colonized new sites after 22–25 years. For 21 years after the release of 83 egg clusters, the population size fluctuated between 24 and 143 adults, and remained confined to the release site. However, four years later, the population was estimated at >3,000 adults, and covered 70.4 ha. After a further three years, the population had declined to 150 adults at the release site, but two other habitat patches (0.3 and 0.6 ha) remained occupied (13–153 adults/ha). In July 1977, eggs and adult females were collected in Wyoming, and kept in a laboratory where more eggs were laid. In July–August 1977, eighty-three wild- and captive-laid egg and caterpillar clusters (~10,000 individuals from ~40 females) were released on to bearberry honeysuckle Lonicera involucrata in a 2.25-ha meadow. Details of the translocation taken from Holdren & Ehrlich (1981). In June–July 1978–1989 and 2002–2005, adult butterflies at the release site were caught and uniquely marked every 1–7 days. Recapture rates of marked butterflies were used to estimate the population size in years with sufficient data (1981–1986, 2002–2005). In 1978–1989, 2002 and 2004–2005, egg clusters and/or caterpillar webs were counted throughout the season at the release site, and in 2003–2005 at two newly colonized sites. The relationship between number of egg clusters and adult population was used to estimate the population size in the remaining years. From 1978–1987, areas surrounding the release site were searched for egg clusters or caterpillar webs, and from 2002–2005 a larger area was searched for adults.
Holdren C.E. & Ehrlich P.R. (1981) Long range dispersal in checkerspot butterflies: transplant experiments with Euphydryas gillettii. Oecologia, 50, 125–129.

(Summarised by: Andrew Bladon)