Gacinyiro 2 (Ubuvumo)

Michael Laumanns - 29/11/2015

(North province, Virunga mountains, Musanze district) Co-ordinates: S 01°27,697; E 029°35,049°. Alt. ca. 2,159 m. Explored by the 2003 Swiss-German speleological project. Together with Ubuvumo Gacinyiro 1 (350 m long) and Ubuvumo bywa Musanze 4 (73 m long) this cave forms a segmented chain of lava tubes with a total length of 1,893 m (depth -60 m). Ubuvumo Gacinyiro 2 is the major cave segment at 1,470 m of length. According to the coordinates it is possible that the Gacinyiro tubes lead towards Ubuvumo bywa Musanze (see above), which is of a very similar morphological appearance. The middle section of Ubuvumo Gacinyiro is branched. Here and in the southern section of the cave landmines are suspected. The gallery diminishes gradually in size and is finally choked by lava boulders. Ubuvumo Gacinyiro 2 has twelve entrances in total with the lava flow coming from the Bisoke-Sabyinyo volcanoes. The complete cave is developed near to the surface of the lava stream with a lot of daylight holes that partly allow to visit the cave without a light. The floor of the cave consists mainly of breakdown, in some places of earth or lava (including ropy lava). Some sections of the walls show lava flow marks. Bats live mainly in the most southerly extension of the cave. The species Rhinolophus clivosus keniensis, Stenonycteris lanosus lanosus as well as Rousettus aegyptiacus leachii have been determined. Swiftlets and an owl inhabit the cave entrances near to the branched part of Ubuvumo Gacinyiro 2, the latter is responsible for some accumulations of bones of small mammals. Furthermore, spiders, snail shells, woodlice and mites were observed. Survey and description according to Laumanns et al. (2004, 2007).