Human activity and landscape degradation in the borderlands surrounding Protected Areas (PAs) may have far-reaching consequences and undermine the ecosystems they aim to protect. According to a new study, which leveraged four decades of observations from the Serengeti-Mara ecosystem in East Africa, such activity at the fringes impinges on the ecological function all the way to the ecosystem's core. The results highlight a need to rethink the role of natural resource management in the landscapes surrounding PAs. While PAs have become an important and commonly used tool for conserving vulnerable biodiversity and ecosystems, nearly one-third are under intense human pressure - particularly from rapidly growing populations and activity along their borders. Separately, the sustainability of the PA strategy to conserve areas is unknown, particularly given questions around PA edge-effects. To better understand how PAs are impacted by the growing human pressures at the borders, Michiel Veldhuis and colleagues compiled long-term data from the Serengeti-Mara ecosystem - one of the largest PAs on Earth and home to over two million migrational large herbivores. Human populations in the areas surrounding the Serengeti-Mara have increased steadily for the past 20 years, as has the shift towards agricultural and pastoral land use. Veldhuis et al. discovered that this human activity has had the effect of "squeezing" wildlife into the core of the 40,000 square kilometer (km) PA and has resulted in substantial impacts on the ecological function and integrity of the ecosystem. The results include landscape-scale changes to fire regimes, wildlife migration and grazing patterns and an increased vulnerability to extreme droughts. According to the authors, these effects are likely to be comparable in many other large PAs worldwide.