Amphibian surveys in the Okavango Delta
21 Aug 2009
Sighting: Amphibian surveys in the Okavango Delta
Location: Xigera Camp, Moremi Game Reserve, northern Botswana
Date: August 2009
Observers: Marleen Le Roux, Prof. Louis Du Preez, Dr. Ché Weldon & Kai Collins
Photographs: Marleen Le Roux
While working at Xigera Camp I began my MSc. research into the influence of hydrology and degree of isolation on amphibian biodiversity in the Okavango Delta. Surveys have thus far been conducted in the Xigera Concession in the heart of the Okavango Delta and in the Vumbura Concession on the north-eastern fringe of the Okavango Delta (the Mombo Concession will also be included). Since very little work has been done on the frogs of the Okavango our results and findings have been very interesting.
At Xigera, a total of nine habitat sites representing all possible amphibian habitats for that locality have been chosen for future fieldwork. Six sampling sessions were carried out during the field expedition at Xigera and specimens were taken back to our mobile lab at the camp where specimens were identified, photographed, swabbed for chytrid fungus (Batrachochytrium dendrobatidis) and then either prepared as a voucher specimen, or released at the location where they were collected. In addition we focused on frog calls, frog call recording, setting up a pitfall trap, the techniques of netting for tadpoles, and also analysing specimens that had been preserved prior to the start of the field trip.
Sampling in the Xigera and Vumbura Concessions has so far resulted in a total of 14 amphibian species identified. Please note that all identifications and results thus far are preliminary and require final assessment and DNA confirmation. Species identified thus far however are: Amietophrynus garmani - Eastern Olive Toad; Amietophrynus gutturalis - Guttural Toad; Amietophrynus maculates - Flat-backed Toad; Hemisus guineensis - Guinea Shovel-nosed Frog; Hyperolius nasutus - Long Reed Frog; Hyperolius paralellus - Painted Reed Frog (pictured top left); Ptychadena guibei - Guibe's Grass Frog; Ptychadena mascariensis - Mascarene Grass Frog; Ptychadena subpunctata - Speckled-bellied Grass Frog; Xenopus muelleri - Tropical Platanna; Phrynobatrachus mababiensis - Dwarf Puddle Frog; Kassina senegalensis - Bubbling Kassina; Chiromantis xerampelina - Foam Nest Frog; Tomopterna spp. - Sand Frogs.
Important findings worth mentioning include Guibe's and Speckled-bellied Grass Frogs (P. guibei and P. subpunctata respectively) and the Guinea Shovel-nosed Frog (H. guineensis) for which there is very limited information on distribution, life histories and tadpoles (see left for photo of H. guineensis). In addition, there may be a possible extension of the distribution of the Eastern Olive Toad (Amietophrynus garmani) to include the Okavango Delta and we were also able to make the first known recording of the call for Guibe's Grass Frog (this species pictured bottom left).
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