Population Viability Analysis for a vulnerable ground-nesting species, the Cape Rockjumper Chaetops frenatus: assessing juvenile mortality as a potential area for conservation management

Abstract

As an endemic bird to the Fynbos biome, prominently featured in literature and marketing material for the avifauna of the continent, the Cape Rockjumper Chaetops frenatus is an iconic species of South Africa. Building on studies from the past decade, recent publications all point to a vulnerability to climate change due to temperature-related effects on their behaviour, physiology, and life history. Here we present a population viability analysis for the species based on knowledge of recent declines and making use of recently available information on their life history. We combined recent breeding success data (2016–2018) with that of a population monitored approximately two decades ago (1998–2000) and modelled the probability of extinction for four scenarios where the principal change was in juvenile (more accurately, nestling) mortality. We focused on juvenile mortality as there are previously identified areas of vulnerability that present potential areas for mitigation. With juvenile mortality set at the recently recorded rate of 80% there is a 49.1% chance of population extinction within 100 years, despite optimistic adult survival and breeding parameters used in the models. We then provide insights into factors that mediate juvenile mortality as potential avenues for the management of the species.