Despite illegal killing (poaching) being the major cause of death among large carnivores globally, little is known about the effect of implementing lethal management policies on poaching. Two opposing hypotheses have been proposed in the literature: implementing lethal management may decrease poaching incidence (‘killing for tolerance’) or increase it (‘facilitated killing’). Here, we propose a test of two opposed hypotheses that poaching (reported and unreported) of Mexican grey wolves (Canis lupus baileyi) in Arizona and New Mexico, USA, responded to changes in policy that relaxed protections to allow more wolf-killing. We employ advanced biostatistical survival and competing-risk methods to data on individual resightings, mortality, and disappearances of collared Mexican wolves. We aim to provide recommendations for improving the effectiveness of US policy on environmental crimes, endangered species, and protections for wild animals. Our results have implications beyond the USA or wolves because the methods promise to transform understanding, scientific methods, and management interventions of processes and patterns in human-caused mortality among wild animals subject to high rates of poaching.

We analyzed data acquired from the USFWS Mexican Wolf Recovery Program (MWRP, 'Survival2016-FOIA Request_To be Released copy.csv') and their Office of Law Enforcement (OLE, 'Final FWSLE FOIA Release copy.xlsx') in separate but overlapping datasets on marked (hereafter collared), monitored Mexican wolves in the wild. The MWRP survival data include the monitoring history for all collared and monitored adult Mexican wolves in the wild since the beginning of the recovery program, 29 March 1998 - 31 December 2016; n=279 (monitored wolf pups were excluded from this dataset). 

We processed the original data following commands provided in a STATA .do file within the Supplementary Materials of the published article (to be used with the formatted for processing 'MXWolfSurvival2016_FOIA_Master_ORIGINAL copy.xlsx').

 The OLE dataset does not contain information for all wolves in the MWRP dataset. 

The 'Cause_of_death_OLE.dta' dataset contains the OLE data, ready to merge with the formatted dataset (following the .do file in Supp Mat).