Vertical distribution of fruit feeding butterflies
Some studies have suggested that ground-based surveys will miss a large component of diversity that is confined to the canopy (DeVries et al. 1997).
Out of 14 species recorded from walk-and-count transects (Tangah 2000), 13 were caught in low level traps.
However 6 species of Satyrinae and Morphinae were caught in traps but not recorded on transects, and 4 of these were caught above ground level.
These data indicate that whilst ground-based transect techniques can survey Satyrinae and Morphinae butterflies fairly reliably, they are likely to miss a component of the fauna that does not occur at ground level.
Species caught in low level traps but not seen on transects may have been crepuscular (active only at dawn) (Corbet & Pendlebury 1992), and these species will also be under-recorded using walk-and-count transects.
Other studies of fruit-feeding butterflies have shown higher diversity at ground level, compared with the canopy (Hughes et al. 1998).
This may be because rotting fruit generally fall to the ground. In this study, 17 of 40 of species (43%) were recorded only in the low level traps. However, 9 species (23%) were recorded only in intermediate or in high level traps (e.g. Elymnias dara, Polyura athamas and Charaxes solon; Table 1) indicating that some fruit may normally rot in situ or may often get trapped in the upper branches.