Movement and vertical stratification of fruit-feeding butterflies in a managed West African rainforest

Abstract

We analysed movement parameters and vertical stratification in fruit-feeding butterflies between a control, a thinned and a plantation site within a West African rainforest. Overall, distances moved between traps were largest in the plantation. Movement parameters were generally largest in species feeding on early successional hostplants of gap and margin habitats. In these species, distances between recaptures were significantly shorter in the thinned compared to the control forest. Conversely, forest floor species feeding on climbers and understorey shrubs showed significantly larger movement in the thinned forest. Higher strata species also flew larger distances in the thinned understorey. Including higher strata samples, they were significantly less abundant in the thinned plot, although understorey sampling alone indicated the contrary. Comparing vertical distribution patterns between thinned and control sites indicated a disruption of vertical stratification after thinning. Canopy species seem to fly in the upper strata of the more closed-canopy control forest, whereas they descend more frequently in the forest opened by the thinning management. Understorey sampling might therefore lead to biased conclusions due to differences in vertical distribution between forest plots. This study showed that thinning can affect the restricted-range forest floor butterflies as well as the more widespread canopy butterfly fauna.