Tourism infrastructure and physiological stress in free-ranging impalas (Aepyceros melampus) of Serengeti National Park

In the developing world, many protected areas (PAs) rely on tourism as a viable source of financial resources for conservation. However, the drive to maximise revenue has led to an increase in tourist numbers and infrastructure developments that often exceed ecological capacity, creating challenges for biodiversity and wildlife populations. To evaluate potential physiological impacts of tourism infrastructure and environmental factors, we measured faecal glucocorticoid metabolites (FGMs), an established indicator of stress in animals, using a validated enzyme immunoassay (EIA). We analysed FGMs from 213 impala (Aepyceros melampus) faecal samples collected in Serengeti National Park, Tanzania, between January and February 2025. Our results showed that impalas near lodges exhibited significantly higher FGM levels even without tourist occupancy (i.e., infrastructure), than those near permanent tented camps or seasonal campsites. These findings suggest that large-scale tourism infrastructure is associated with elevated stress in impalas. Future research should focus on identifying the specific features of large tourist facilities that drive physiological stress in wildlife, to better inform tourism development and conservation strategies in PAs. • Protected areas in many developing countries increasingly depend on tourism revenue to fund conservation. • Infrastructure expansion linked to tourism often exceeds ecological capacity, posing risks to wildlife. • In Serengeti National Park, large-scale tourist infrastructure can elevate wildlife stress, even without tourist presence.