This study was designed to identify the butterfly species inhabiting the Bwindi Impenetrable Forest, South West Uganda, assessing their habitat preferences as well as determining their relative abundance and seasonal patterns.

Relative population estimates, diversity and distribution were assessed by use of line transects in five major habitat types ranging from 1400m at Ishasha Gorge (lowland forest) to 2600m at the Bamboo zone (montane bamboo forest). Baited traps and sweep nets were used.

In total, 183 butterfly species belonging to 61 genera and nine families were recorded. 62 species were new to the Forest's butterfly list. 

The study registered eight regional endemic species and eight eclectic (not necessarily forest dependent) species. 

Photo: Blue temora, a characteristic species for lowland and mid altitude forest (Salamis temora, Fam. Nymphalidae)

Species diversity decreased with altitude, but some species occurred at all altitudes. Most butterflies showed habitat preferences.  Butterflies of Bwindi Impenetrable Forest were divided into 'indicator species' and 'characteristic species', in terms of their habitat preference: indicator species were those found exclusively within a vegetation formation while characteristic species were those commonly found within the formation but not confined to it. Some, however, were generalist and/or adapted to various habitat types. Butterflies exhibited seasonal changes in species composition and abundance.

Based on three well studied butterfly genera: Swallow tails Papilio, Sword tails Graphium and Charaxes, butterfly diversity in Bwindi Impenetrable Forest was found to be higher than that of other forests in Uganda.