ABSTRACT: After a period of overfocus on the establishment of reserves, attention is increasingly being devoted to the capability of protected areas to maintain viable populations of endangered species. Here, we examined the trends and reproduction of the red kite Milvus milvus, a highly endangered raptor near-endemic to Europe, to illustrate the dual benefits and challenges faced by a national park to protect this iconic species. Over the past 4 decades, the kite population of southern Spain has declined steeply and has become progressively confined to Doñana National Park and its buffering Natural Park areas. Population deterioration was also evident within the protected area through (1) spikes of rapid eradication of whole sub-populations from buffer areas, likely propelled by illegal poisoning, and (2) more gradual but steady deterioration of numbers and reproduction, especially in peripheral buffer areas, probably caused by the interplay of several shocks related to food availability, habitat degradation, competition, predation, and chemical contamination. The result was a 46-55% decline with progressive confinement to the core National Park and an alarming effective population size of <10 pairs. Demographic modelling suggested low adult survival and predicted further declines, with possible extinction over the next 2 decades. We outline tentative goals for management, but these will need urgent information on ranging and mortality to provide more efficient targets. These results illustrate how establishment of a large park can prevent regional extinction, but not necessarily guarantee species-safety, leading to protracted forms of extinction debt. We suspect that similar dynamics will become more widespread as anthropogenic pressures increase around protected areas and their performance monitoring becomes more prevalent.