Low-Quality Habitat Corridors as Movement Conduits for Two Butterfly Species

Corridors are a primary conservation tool to increase connectivity, promote individual movement, and increase gene flow among populations in fragmented landscapes. The establishment of effective conservation corridors will depend on constructing or preserving connecting habitat that attracts dispersing individuals. Yet, it remains unclear whether corridors must necessarily be composed of high-quality habitat to be effective and promote dispersal and gene flow. We address this issue with two mobile, open-habitat butterfly species, Junonia coenia Hübner and Euptoieta claudia Cramer. Using experimental landscapes created explicitly to examine the effects of corridors on dispersal rates, we show that open-habitat corridors can serve as dispersal conduits even when corridors do not support resident butterfly populations. Both butterfly species were rare near forest edges and equally rare in narrow corridors, yet both species dispersed more often between patches connected by these corridors than between isolated patches. At least for species that can traverse corridors within a generation, corridor habitat may be lower in quality than larger patches and still increase dispersal and gene flow. For these species, abundance surveys may not accurately represent the conservation value of corridors.