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Table 4 The data sources, variables and outcomes of the returned articles relating to Patrol effectiveness in preventing wildlife crime

From: Systematic review of situational prevention methods for crime against species

Publication Data source/s Dependent variable/s Independent variable Confounding variable/s Statistical analysis Results: effectiveness of patrols
Hilborn et al. 2006 Arrest records
Recorded since 1957
Antipoaching activity records
Only available for some years
Species abundance
Buffalo, Elephant and Rhino numbers
Abundance of species
African Buffalo, Elephant, Black Rhino
Relative Poaching effort
Ratio of Poaching Intensity (arrests per patrol) to Antipoaching effort (patrols per day)
Influence of community engagement mentioned, however the authors claim the decline in poaching effort occurred before the community programs were initiated, therefore the authors attribute the reduction in poaching to patrols Population dynamics model
Plotting the time series data on Abundance of Species and Relative Poaching Effort
The trends observed indicated that declines in species abundance correlated with periods when patrolling was limited due to park funding. As patrolling increased, species abundance was found to improve
Leader-Williams et al. 1990 Field records
Provided information on:
 Illegal activity
  Total Poachers Encountered
  Camps—indication of illegal activity
  Fresh Carcasses (flesh covered rhino/elephant carcasses with trophies axed off)—indication of successful poaching activity
 Patrol data
Number of Patrol days
Illegal activity
(poachers, camps, carcasses)
Abundance of species
Historical sightings of Rhino and Elephant by foot patrols used as a measure of population trends
Patrol Effort
Encounter rates per effective patrol day
Month/Season
Patrol Length
Number of Scouts
Area
Year (fitted as categorical)
Anti-Poaching Unit (APU)
Simple regression
Rates of change in species abundance and patrol effort (in all areas in all years), to assess if animal abundance declined faster in areas where there was least effort
Multiple regression
Illegal activity, patrol effort and species abundance to establish if illegal activity was distributed in areas with least patrol effort and most quarry
Negative relationship between camps, carcasses and effort
Increased patrol effort was associated with a reduction in finds of fresh carcasses and camps
Overall, the results suggested that patrol effort reduced the number of finds of fresh carcasses and illegal activity
Jachmann and Billiouw 1997 Patrol reports
Detailing routes and observations
Number of elephants killed Illegally
(per annum)
Financial and Patrol variables:
 Total law enforcement budget per km2 (US$)
 Personal emoluments per scout per month (US$)
 Transport expenditure per km2 (US$) km2 per scout
 Km2 per carrier
 Effective patrol days per km2
 Effective investigation days
 Number of bonuses paid: average bonus rates (US$)
Poisson Regression Model Deterrence effects of both foot and investigative patrols were found to be equally important
The predictor variables below were found to be significantly negatively associated with the number of elephants killed illegally:
 Bonuses Paid
 Number of Scouts
 Law enforcement budget
 Personal emoluments per scout per month
Linkie et al. 2015 Field data from ranger patrol logbooks
 Snare Trap Occurrence
 Patrol Frequency
 Patrol Effort
Biological data on tiger prey base collected using camera trap images from 2004–2006 and 2009–2011
 Tiger Occupancy/Abundance
Snare Trap Occurrence
Tiger Prey Occupancy /Abundance
Patrol frequency (number of times visited over previous 1 and 2 year periods)
Patrol effort
(number of kilometres patrolled in previous 1 and 2 year periods)
Spatial covariates related to accessibility:
 Elevation
 Slope
 Proximity to nearest road
 Proximity to forest edge
 Proximity to nearest village & protected area status
Additional covariate assessed between 2009–2010:
 Tip Off—influence of intelligence-based patrolling
Markov Model
Modelling the deterrence of poachers by patrols, due to the removal of snares leading to reduction in the success of poaching
Snare trap occurrence between 2000 and 2010 declined by 24%, but the result was not statistically significant. The authors identified that the analysis did not control for potential spatial effects created by the establishment of new teams in previously unpatrolled areas. These new teams would likely contribute to the overall number of snares detected in the study area. Highlighting the importance for local-level, individual patrol measurements
Linkie et al. 2015
…Continued
Patrol Frequency was found to have the most influence over the detection of snare traps, followed by Patrol Effort (number of kilometers walked)
Both variables were found to have an increased influence on the detection of snares if performed routinely over more time (e.g. 2 years compared to 1 year)
Accessibility was found to be an important factor in relation to patrol team performance. More snare traps were recovered from sites considered more accessible due to lower elevation, and flatter terrain
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