Quantification of faecal glucocorticoid metabolites as a measure of stress in the rock hyrax Procavia capensis living in an urban green space

Despite the abundance of rock hyrax Procavia capensis within South Africa's urban areas, there is not much information available about the effect of anthropogenic activities on rock hyrax wellbeing. To determine the potential impact of anthropogenic disturbance on adrenocortical activity, we conducted an ACTH challenge to identify a suitable enzyme-immunoassay (EIA) for measuring faecal glucocorticoid metabolite (fGCM) concentrations in the rock hyrax. This study identified an 11 beta-hydroxyaetiocholanolone EIA as the most suitable assay in this regard. The fGCM levels measured, indicate the physiological stress response in different rock hyrax populations, living in an area with varying degrees of anthropogenic activity (low, medium, high) within the National Botanical Garden of Pretoria, South Africa. The species' habituation to human numbers (weekly mean number of people) was examined by determining individual flight initiation distance (FID). Seasonally, there were overall higher fGCM concentrations in late spring compared to winter. The fGCM concentrations, although not significantly different but possibly biologically relevant, in the section with the lowest anthropogenic disturbance were similar to 10% higher compared to those in the section with medium disturbance, and similar to 20% higher compared to those in the section with the highest disturbance. Animal FID did not differ significantly between seasons but they did differ significantly between sections, and decreased in accordance with fGCM concentrations. The non-invasive approach established in this study provides a foundation for assessing rock hyrax wellbeing, and can help better understand how anthropogenic presence is perceived as a stressor in this species.

Automated summary

This study used an ACTH challenge to identify a suitable enzyme-immunoassay (EIA) for measuring faecal glucocorticoid metabolite (fGCM) concentrations in rock hyrax, and found that 11 beta-hydroxyaetiocholanolone EIA was the most suitable assay. The research also showed different physiological stress responses in rock hyrax populations living in areas with varying degrees of anthropogenic activity. Seasonally, late spring had overall higher fGCM concentrations compared to winter, and fGCM levels were different between areas with different levels of anthropogenic disturbance. Additionally, the study found that the animals' flight initiation distance (FID) decreased in accordance with fGCM concentrations and varied significantly between sections.