Occurrences of forest butterflies in the farm bush savannah outside a forest reserve in Ghana, West Africa
The willingness of a species to leave a forest fragment is a prerequisite for subsequent dispersal across the intervening non-forested landscape. Species with stringent fidelity to the forest patch will be isolated from populations in other fragments and predisposed to factors that promote extinction of local populations. Here, we document which fruit-feeding, forest-dwelling butterflies occur in the farm bush savannah outside an afrotropical forest reserve in order to gain a first approximation of those potentially dispersing across it. Standard fruit-baited traps hung at 80 m inside the forest, the forest edge and 12 and 50 m into the savannah matrix were used to characterize communities in the different habitats. A total of 1616 specimens were collected from the 19 traps, representing 90 species. Rarefied species richness was generally comparable across habitats. Multivariate ordination analyses, which integrate species composition and relative abundance in addition to richness, uncovered two broad community types, i.e. forest (edge plus 80 m inside) and matrix. Relative fidelity to forest habitat was investigated for the 45 species that were represented by at least five individuals. More than half of the forest-associated species showed relaxed fidelity to forest habitat and were commonly trapped in the matrix. Although forest generalists and dry forest species were expected to be more commonly trapped outside the forest relative to wet or moist forest species, there was no relationship between the relative occurrence of species in matrix versus forest habitat and their habitat association category.
Key wordsAfrotropics forest fragments fruit-feeding butterflies habitat fidelity matrix habitat Nymphalidae patchy landscapes
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