Corridor and distance effects on interpatch movements: A landscape experiment with butterflies

The hypothesis that corridors increase animal movement between habitat frag ments, a central tenet of conservation biology, has been virtually untested . This study demonstrates that corridors increase interpatch movement rates of two butterfly species. The hypothesis was tested in a large-scale, repl icated experiment, in which 27 equal-sized (1.64-ha) patches of early succe ssional habitat were created within large areas of pine forest. Patches var ied in whether or not they were connected to another patch by a corridor, a nd in their distance from other patches (64-384 m). The results of mark-rel ease-recapture studies showed that two open-habitat butterfly species, Juno nia coenia and Euptoieta claudia, moved more frequently between patches con nected by corridors than between unconnected patches. Interpatch movement w as significantly, negatively related to interpatch distance. Interpatch mov ement rates of J. coenia were significantly, positively related to the dens ity of its host and nectar resource, Linaria canadensis. Corridor effects w ere stronger for males than for females and were most pronounced within thr ee days after butterflies were marked. Pine forest was not a complete barri er to butterfly movement; both species moved between unconnected patches, e ven at the longest distances. However, the results of this study suggest th at corridors will increase long-distance movements of habitat-restricted sp ecies.