Large-mammal populations are ecological linchpins1, and their worldwide decline2 and extinction3 disrupts many ecosystem functions and services4. Reversal of this trend will require an understanding of the determinants of population decline, to enable more accurate predictions of when and where collapses will occur and to guide the development of effective conservation and restoration policies2,5. Many correlates of large-mammal declines are known, including low reproductive rates, overhunting, and habitat destruction2,6,7. However, persistent uncertainty about the effects of one widespread factor—armed conflict—complicates conservation-planning and priority-setting efforts5,8. Case studies have revealed that conflict can have either positive or negative local impacts on wildlife8,9,10, but the direction and magnitude of its net effect over large spatiotemporal scales have not previously been quantified5. Here we show that conflict frequency predicts the occurrence and severity of population declines among wild large herbivores in African protected areas from 1946 to 2010. Conflict was extensive during this period, occurring in 71% of protected areas, and conflict frequency was the single most important predictor of wildlife population trends among the variables that we analysed. Population trajectories were stable in peacetime, fell significantly below replacement with only slight increases in conflict frequency (one conflict-year per two-to-five decades), and were almost invariably negative in high-conflict sites, both in the full 65-year dataset and in an analysis restricted to recent decades (1989–2010). Yet total population collapse was infrequent, indicating that war-torn faunas can often recover. Human population density was also correlated (positively) with wildlife population trajectories in recent years; however, we found no significant effect, in either timespan, of species body mass, protected-area size, conflict intensity (human fatalities), drought frequency, presence of extractable mineral resources, or various metrics of development and governance. Our results suggest that sustained conservation activity in conflict zones—and rapid interventions following ceasefires—may help to save many at-risk populations and species.
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We thank E. Angus, C. Baker, C. Buoncore, J. Castillo Vardaro, B. Lin, A. Tilman, and the Princeton University libraries staff for assistance with data collection and analysis; D. Wilcove, S. Pacala, S. Morris, S. Budischak, J. Socolar, K. Gaynor, J. Edmond, T. Coverdale, R. Long, and U. Srinivasan provided comments. I. Craigie provided access to raw data from ref. 19, and we acknowledge the use of publically available data sources, especially from R. East, the IUCN African Elephant Specialist Group, the World Database of Protected Areas, PRIO-GRID, and GED. This work is a product of US NSF DDIG grant DEB-1501306 to J.H.D. and R.M.P. Additional support was provided by NSF DEB-1355122, DEB-1457697, and the Princeton Environmental Institute.
Extended data figures
Extended data tables
Raw data for the 1946–2010 analyses. These data include for each mammal population: the country, protected area, species name, time interval (starting and ending years), λ estimate, conflict-frequency estimate, species body mass, protected-area size, spatially lagged conflict frequency estimates, national-level conflict-frequency estimate, spatial and temporal dimensions of conflict frequency, grouping of records for the bootstrap test of pseudoreplication, and the literature sources for mammal population data in each year. See Supplementary Table 5 for explanations of each column heading.
Raw data for the 1989–2010 analyses. These data include for each mammal population: the country, protected area, species name, time interval (starting and ending years), λ estimate, conflict-frequency estimate, species body mass, protected-area size, human population density, Corruption Perceptions Index, conflict intensity, drought frequency, percent urban area, travel time to the nearest urban centre, presence or absence of extractable mineral resources, spatially lagged conflict frequency estimate, national-level conflict-frequency estimate, spatial and temporal dimensions of conflict frequency, grouping of records for the bootstrap test of pseudoreplication, and the literature sources for mammal population data in each year. See Supplementary Information Table 5 for explanations of each column heading.
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