What is a patch in a dynamic metapopulation? Mobility of an endangered woodland butterfly, Euphydryas maturna

Abstract

In metapopulations of butterflies inhabiting transient forest openings, the dynamic character of biotopes prevents unequivocal delimitation of habitat patches, complicating analyses of inter‐patch dispersal. We analyse mobility of one such metapopulation, using mark‐recapture data on an endangered butterfly, the scarce fritillary Euphydryas maturna, at its last site in the Czech Republic. The butterfly inhabits woodland clearings, its population numbered 190 individuals in 2002. We modelled movements in eight habitat patchworks delimited according to different criteria and superimposed over the forest, using the Virtual Migration model. Resulting mobility parameters were generally robust against patchwork definitions, the main distinction was between patchworks based on presence of adults and consisting of small patches and patchworks based on distributions of larval nests and consisting of large patches. Emigration constant decreased towards the latter, whereas males suffered higher migration mortality than females in the former. Patchworks delimited according to presence of adults performed better than patchworks based on distribution of larval nests. A comparison of our parameters with those found for the species in Finland showed that the Czech butterflies were more prone to leave individual patches and suffered higher migration mortality, which combined into considerably shorter survival. We conclude that transferring dispersal parameters among different regions and populations is more risky than using less suitable definitions of habitat patches within single region.