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Providing evidence to improve practice

Individual study: Guard dogs and gas exploders as coyote depredation control tools in North Dakota

Published source details

Pfeifer W.K. & Goos M.W. (1982) Guard dogs and gas exploders as coyote depredation control tools in North Dakota. Proceedings of the Tenth Vertebrate Pest Conference, University of California, Davis, 55-61.


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Use loud noises to deter predation of livestock by mammals to reduce human-wildlife conflict Terrestrial Mammal Conservation

A replicated study in 1979–1980 of three ranches in North Dakota, USA (Pfeifer & Goos 1982) found that gas exploders temporarily deterred sheep predation by coyotes Canis latrans. Installation and use of gas exploders stopped predation for 17–102 days. Sites selected for the study had suffered ≥5 sheep losses to predation by coyotes in the previous two weeks. Following this, propane gas exploders were installed in the pastures. Exploders were operated until the grazing season was over or until ≥2 verified coyote kills occurred. Two to three exploders/site fired at 8–20-minute intervals overnight and were moved every 4–5 days. Sheep farmers were compensated for losses to coyotes provided that exploders were used as the sole means of control. The trial operated on three sites, with pastures extending over 56–255 ha, and containing 190–1,000 sheep.

(Summarised by Nick Littlewood)

Use guardian animals (e.g. dogs, llamas, donkeys) bonded to livestock to deter predators to reduce human-wildlife conflict Terrestrial Mammal Conservation

A replicated study in 1981 of 36 ranches in North Dakota, USA (Pfeifer & Goos 1982) found that guard dogs Canis lupus familiaris reduced sheep losses to predation by coyotes Canis latrans. The average annual predation rate after commencing use of guard dogs (0.4% of the sheep flock) was lower than that before guard-dog use commenced (6%). In 1981, thirty-six ranchers were interviewed about livestock management and losses to predation in the 1976–1981 period. Between them, ranchers had 52 great Pyrenees dogs (44 working and eight training) and two working komondor dogs. All ranchers commenced using guardian dogs during the period. Guarded pastures were 4–486 ha in extent and guarded sheep flocks contained 10–1,300 animals. Dogs were raised with the sheep flock and remained with them most of the time.

(Summarised by Nick Littlewood)