AbstractIn many African countries, anthropogenic pressure and poor governance have led to the degradation of wildlife corridors, which are important for the long‐term viability of wildlife populations. Yet the nature of such degradation is poorly understood, hindering our ability to reverse these trends. We studied a deteriorating wildlife corridor between Katavi and Mahale National Parks in western Tanzania. Using satellite imagery, we found that the corridor still contains large areas of natural vegetation, diverse terrain and numerous water sources. There has nonetheless been increasing encroachment of the corridor by people between 1990 and 2017, exemplified by a 9% reduction in the area covered by miombo woodlands and a fourfold increase in the area covered by settlements and agricultural land. We used three additional methods to assess deterioration over the last three decades: elephants' movement routes, peoples' perception of animal populations and incidents of human–wildlife conflicts. Elephants were primarily found only in the parts of the corridor adjacent to the two national parks. Tracking of elephant spoor revealed a much‐diminished corridor use, suggesting that seemingly ‘healthy’ habitat within a wildlife corridor will not necessarily predict the presence of elephants or perhaps of other species. Other factors particularly the increasing presence of humans in the area are possibly more important for predicting elephant use of a corridor. Interviews with local residents and conservation experts suggested that, although use by some animal species has declined, many ungulates were still seen in the corridor and neighbouring villages, some of which were associated with human–wildlife conflict. All villages around the corridor were affected by the human–wildlife conflict; this comprised crop damage, livestock injury or killing and attacks on humans. We conclude that corridors could be restored if people were restricted from settling, but this would require governments to enact policies that balance the conservation of Natural Capital with survival of human populations; the latter may involve internal migration in response to growing population pressures.