U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Date of this Version



Breck, S.W., A.J. Davis, J.K. Oakleaf, D.L. Bergman, J. deVos, J.P. Greer, and K. Pepin. 2023. Factors affecting the recovery of Mexican wolves in the Southwest United States. Journal of Applied Ecology 60(10):2199-2209. doi: 10.1111/1365-2664.14483


U.S. government work


  1. Recovering and maintaining large carnivore populations is a global conservation challenge that requires better knowledge of the factors affecting their populations, particularly in shared landscapes (i.e. non-protected areas where people occupy and or utilize the land).
  2. The Mexican wolf (Canis lupus baileyi) is an endangered wolf subspecies being recovered on shared landscapes in the Southwest United States and Mexico. We used data from the U.S. program to model population growth, evaluate the impact of management removal and illegal killing relative to other demographic factors, and test hypotheses about factors influencing rates of management removal and illegal killing.
  3. From 1998 to 2019, the population growth averaged 12% per year. Rates of natural reproduction, illegal killing and other mortality remained consistent over the 22 years; while releases, translocations and management removals varied markedly between two time periods, phase 1:1998–2007 and phase 2:2008–2019.
  4. The number of wolves removed for conflict management was higher during phase 1 (average ~ 13 per year, rate = 24.8%) than phase 2 (average of ~5 per year, rate = 5.2%). This decrease in management removal resulted in the wolf population resuming growth after a period of population stagnation. Two factors influenced this decrease, a change in policy regarding removal of wolves (stronger modelling support) and a decrease in the number of captive-reared adult wolves released into the wild (weaker modelling support).
  5. Illegal mortality was relatively constant across both phases, but after the decrease in management removal, illegal mortality became the most important factor (relative importance shifted from 28.2% to 50.1%). Illegal mortality was positively correlated with rates of reintroduction and translocation of wolves and negatively correlated with the rate of management removal.

6. Synthesis and applications. Using management removal to reduce human–carnivore conflict can have negative population impacts if not used judiciously. Recovering and maintaining carnivore populations in shared landscapes may require greater tolerance of conflict and more emphasis on effective conflict prevention strategies and compensation programs for affected stakeholders.