An improved conservation status of Southern Bald Ibis Geronticus calvus as informed by a diversity of citizen science projects suggests positive impacts of conservation attention

Abstract

Abstract The Southern Bald Ibis is endemic to South Africa, Lesotho and Eswatini, occurring across high and mid- altitude mesic grasslands and has been of conservation concern in the seventies, resulting in a range of monitoring, research and conservation actions. We examine a range of data sources to determine the conservation status of this species, employing a variety of statistical and analysis pathways. We compare trends in reporting rates from Southern African Bird Atlas Projects (SABAP), examine trends in numbers of nests reported through colony monitoring, and explore contributions made to the ‘Threatened species cause’ from the BirdLasser mobile app. Using the BirdLasser data, we find the species is widely reported across the range outside of sites with known colonies and roosts, suggesting a large proportion of the population is not available for counting during the breeding season. Using insights from the SABAP data and occupancy modelling, combined with group counts from BirdLasser data, we suggest the population is likely > 10 000 individuals. None of the trend analysis statistics we used revealed a decrease in population size for the period 1987–2021. We note that certain colonies are still being abandoned, but this is now at a lower rate (< 10% of colonies). After dramatic declines from the early part of the last century, this suggests the declines are now being curtailed, and there is some evidence the species may be recolonizing lost range. However, we note that this species is being negatively impacted by loss of grasslands to alien vegetation, and will likely be negatively impacted by climate change and other developments. While it is difficult to infer causality with conservation attention, the reversal in the fortunes of the species is encouraging for those involved in the long conservation journey of this species. Continued monitoring of this charismatic species is required in addition to ongoing habitat management to ensure declines are conclusively reversed.