Natural Egg Mortality of the African Grey Tree Frog, Chiromantis xerampelina (Amphibia: Rhacophoridae)

Abstract

Rainfall patterns are recognised as important for normal ecosystem functioning in arid environments. Most attempts made to understand the effect of rainfall on amphibian ecology have focused on long-term rather than short-term trends. Here, factors effecting embryonic mortality and clutch size of the African foam nesting frog Chiromantis xerampelina were examined at two ponds from April – June in 2011-2012 in Malawi. A total of 73 foam nests were monitored following spawning. On average 29% of eggs in 2011 and 26% in 2012 suffered mortality from both ponds and this mortality significantly varied between nests. Linear regression showed that the date of spawning had a significant effect on mortality due to moisture requirements of the eggs. The height of nests over the water surface had a negative impact on clutch size and increased rainfall decreased egg mortality in both years at both ponds. In a changing climate, with rainfall projected to become more infrequent in this region, organisms may not be able to rely on rainfall patterns as cues for reproduction, which may have a negative impact on amphibian populations.