Altitudinal Distribution and Monthly Occurrence of Butterflies in the Kihansi Gorge Forest, Tanzania, with a Checklist of Species

Abstract

The goal of this project was to establish a checklist of butterflies occurring in Kihansi gorge to serve as baseline for monitoring of gorge ecosystem health. The key questions were what and how many species of butterflies occur in the gorge with respect to time and space. The study was conducted between October 2005 and February 2007. Butterflies were recorded twice a week, along a walking trail, using malaise traps and sweep net. The traps were located at upper (> 750 – 1100 m), mid (> 580 – 750 m) and lower (300 – 580 m) gorge. A total of 213 species were documented, of which 50.2% belong to the family Nymphalidae, 19.2% Lycanidae, 17.8% Hesperiidae, 7.5% Pieridae, 5.6% Papilionidae, and 0.5% Riodinidae. Of the 213 species, only 130 had complete information about time and space of occurrence in the gorge. The Nymphalids and Papilionids were present in the gorge throughout the year, while the Pierids, Hesperiids and Lycaenids occurred in the gorge between November and May. Of the 130 species, 51% were common throughout the gorge, while 26%, 3%, and 20% were unique to upper, mid and lower gorge, respectively. Among the documented species are 3 of conservation concern including a new species, Charaxes mtuiae, and two rare species Etesiolaus pinheyi and Artitropa reducta that are only known from the Eastern Arc Mountain Forests. Kihansi gorge therefore serves as their valuable range extension; hence conservation of this area is important.