Avian scavengers living in anthropized landscapes have shorter telomeres and higher levels of glucocorticoid hormones

Abstract

Habitat anthropization is a powerful stressor affecting the health and fitness of organisms, ultimately impacting their population dynamics. In vertebrates, stressful living conditions are usually associated with elevated glucocorticoids-based responses (GCs) as well as shorter telomeres, which are in turn associated with decreased overall body condition fitness and life expectancy. However, our understanding of how habitat anthropization per se and population processes synergistically, or independently, may affect GCs and telomere dynamics in natural populations is still very limited. Here, we assessed the physiological footprint of habitat anthropization and conspecific density in 65 GPS-tagged Eurasian griffon vultures (Gyps fulvus) from two populations of the Iberian Peninsula. We examined how extrinsic (human footprint values and conspecifics density within individual activity areas) and intrinsic (sex and home range size) factors determine GCs deposited in feathers (CORTf) and telomere length as proxies of overall individual condition and quality. We found strong differences in both physiological markers between populations, with higher CORTf levels and shorter telomeres in vultures living in the northern, more anthropized area. We also found sex-specific patterns of CORTf, with females having higher levels than males. In both sexes, telomere length decreased as the density of conspecifics increased. Previous studies in these populations have shown lower survival rates in individuals who exploit more anthropized areas, and here we show a potential physiological causal link. We highlight the existence of complex effects of chronic stress associated both with living in anthropized environments and with population-related processes likely associated to the spatial distribution of resources.