Securing viable metapopulations of the Marsh Fritillary butterfly, Euphydryas aurinia, (Lepidoptera: Nymphalidae) in Northern England

The Marsh Fritillary butterfly, Euphydryas aurinia (Rott.), is regarded as the classic species that requires landscape-scale management in order to maintain viable populations. This paper describes the background to an extinction of this species in Northern England, United Kingdom, and the action taken to reintroduce and monitor the progress of sub-populations between 2007 and 2009. A captive breeding stock was secured using the last 155 known wild caterpillars in 2004 and supplemented by 95 caterpillars collected under licence from the nearest extant populations in western Scotland. Through captive breeding the source population for subsequent reintroduction was increased dramatically and 42,400 caterpillars were used in 2007 to reintroduce the butterfly to four locations in North and West Cumbria. Each of the release sites is within known historical network areas where the butterfly had thrived in past decades. The intention was to restore multiple habitat patches across each network area and eventually establish viable metapopulations across these landscapes. Adults and larval webs have been monitored since 2007 and show that introduction has been successful at three out of the four locations. The failure at the fourth site appears to be unrelated to habitat condition and the causes are currently being investigated. Work is continuing to secure appropriate management of suitable habitat within each landscape area and the number of sub-populations in one area will be increased in the 2010 season.