Reproductive behaviour of the Kloof Frog (Natalobatrachus bonebergi), an endangered South African endemic

Abstract

Amphibians are vulnerable to extremes in environmental factors such as air temperature, rainfall and relative humidity which greatly influence their physiological parameters and subsequentially their phenology. This vulnerability extends to reproductive behaviour and is reflected in developmental processes of larvae, which are laid in jelly-like eggs. Natalobatrachus bonebergi is an Evolutionarily Distinct and Globally Endangered (EDGE) species and is also monotypic within the genus. Its threat status is based on the threats faced by this species and a severely fragmented distribution. This species is a riparian forest specialist - threatened by deforestation, urbanisation, agricultural clearing, pollution and siltation. Little knowledge exists on the reproductive behaviour of N. bonebergi. Monitoring and surveillance efforts for the species have been undertaken since 2013 in Vernon Crookes Nature Reserve, KwaZulu-Natal, South Africa. Using a protocol developed by the Endangered Wildlife Trust's Threatened Amphibian Programme and tested by Ezemvelo KZN Wildlife Honorary Officers, extensive data have been collected on N. bonebergi reproduction in the form of egg clump counts along riverine transects. With this wealth of data, this study aimed to collect additional data on N. bonebergi reproduction through acoustic monitoring, egg clump isolation experiments and in situ observations of reproductive behaviour from April 2023 to April 2024. A quantitative approach was used to statistically investigate various reproductive behaviours and the relationships these have with environmental factors throughout the species' extended breeding season. Numerous new insights into parental care, male competition, complex communication and interactions between conspecifics and responses to environmental stimuli have been gathered. Knowledge of this species' phenology is important in understanding the evolutionary and ecological processes governing their behavioural patterns, aiding conservation management of this species and its habitats.