Breeding phenology and population dynamics of the endangered Forest Spiny Reed Frog Afrixalus sylvaticus Schiøtz, 1974 in Shimba Hills, Kenya

Abstract

Afrixalus sylvaticus Schiøtz, 1974 is a species of hyperoliid frog inhabiting coastal forest Kenya. It is classified as endangered under IUCN B2ab(iii) ver 3.1 and occurs in the Shimba Hills National Park and hinterlands. Habitat loss and other human activities are threatening the species. Therefore, understanding the breeding ecology and population dynamics is important for its conservation. This study assessed the breeding ecology and population dynamics of the species in the protected and community landscapes in Shimba Hills National Reserve in Kenya. Data was collected through ecological surveys conducted from June 2016 to July 2017 using a visual encounter surveys (VES) method. The results show that the species was more abundant during the wet season than dry (58% and 42%, respectively). The population estimate was 192 individuals and a density of 0.98 individuals/km2. Regarding the morphology, the mean snout-vent length (SVL) for males was 15.12 mm and females 15.96 mm, but there was no significant difference (t-test = 0.87, p = 0.390, df = 39). The mean weight of both gravid and non-gravid females was 6.05 g and males was 4.82 g. The weights were statistically different between both sexes (t-test = 3.50, p-value = 0.001, df = 39). The sex ratio was 1:2 (male: female). There was more activity in the wet season (April and May), and the breeding habitats were reeds and water lilies. The threats identified to their habitat include; human activities such as bush burning, livestock grazing, drainage, and plantation of exotic tree species (Eucalyptus sp.) that have led to habitat loss and degradation. The study recommends that the reforestation processes such as plantation of exotic species such as Eucalyptus sp. and Casuarina sp. and bush burning in the wetlands and species habitats must be discouraged among the stakeholders (community and park management). Moreover, more synchronized studies are necessary to highlight the driver(s) of imbalanced sex ratios and species habitat shifts.

Breeding Ecology and Population Status of Kenyan Amphibians

“…In terms of period and time of the survey, it was evident that more individuals of A. sylvaticus were encountered during morning sampling than the other sampling periods though there was no statistically significant difference (F-Value, 0.25 DF = 2, p-value = 0.781). Weather also plays a part in the species sightings, as during the cool and rainy period, we captured the highest number of individuals (47%) as compared to the cool and dry period (8%) where we captured only five individuals [10]. The results are shown in Table 1.…”

“…From the surveys of one species (A. sylvaticus) we conducted in 2018 in SHE ecosystem, it was evident that many parameters influences the distribution and abundance of amphibians in this ecosystem [10]. One key aspect is the heterogeneous habitats in the SHNR-the area consists of six forest types and woodland and grassland habitats within the reserve [11,12] which allows for the variety of species from different biogeographic zones.…”