Conference Name: The Sixth International Conference on the Biology of Butterflies
Karner blue butterfly (KBB) is an endangered species in the Eastern and Great Lakes USA that occurs within patches of blue lupine that are placed throughout a matrix of unsuitable forest habitat and disturbed fields. The species is assumed to behave as a metapopulation, thus its survival may be dependent upon re-colonization of extinct patches by dispersal. In recent years, declines of KBB have likely increased due to both an increase in the isolation of patches and a decrease in patch size as a result of forest succession. We measured dispersal among isolated patches by mark-recapture over two years within a complex 2-km square area of mostly forested landscape with a few likely insignificant corridors in west Michigan, USA. Past studies indicate that median and mean dispersal flights are restricted to less than 200m and that mature forests act as a barrier to dispersal making extinction in forested landscapes highly probable. However, there is a paucity of data on KBB dispersal, especially within forested landscapes. We documented 233 cases of dispersal among patches through a matrix of closed canopy oak with 92% of the flights greater than 200m. Mean and median dispersal for males was 440m and 370m, and for females was 518m and 370m. Maximum dispersal distance measured was 1.8km for an individual male, with 17 butterflies dispersing more than 1km. The management assumption, that KBB rarely disperse farther than 200m and that a closed-forested landscape acts as a barrier to flight, is false.
Tammy Stambaugh (lead presenter); James P. Dunn