By Stan Gehrt, Wildlife Extension Specialist
(Originally Published in Sheep Team Newsletter June 2007)
The coyote is one of the most successful carnivores in Ohio, as indicated by its widespread occurrence throughout the state. Some producers are fortunate and have few conflicts with coyotes, whereas others seem to have extreme conflicts each year. Unfortunately there is no single solution for managing coyote predation of sheep, and a combination of preventive and responsive strategies are sometimes necessary. Fencing is one option that has been used successfully under certain situations. Coyotes are devious and it can be difficult excluding them with fencing, but some designs are more successful than others.
Net-Wire Fencing is one fencing design that has been effective at deterring coyotes in certain situations, but it can be expensive. Horizontal spacing of the mesh should be less than 6 inches, and vertical spacing less than 4 inches. A barbed wire at the bottom can discourage digging, as will a buried wire apron (often an expensive option). The fence should be at least 5 feet high to discourage coyotes from jumping over it (coyotes usually jump and climb over fences 5 feet high or taller, they cannot typically clear a fence of that height). Because of its expense, net-wire fencing is usually used for smaller areas used for temporary holding.
One fringe benefit to using this type of fencing is that if predation occurs, it is easy to find where the coyote is getting underneath the fence, which makes removal (such as with snares) that much easier.
An alternative to net-wire fencing is electric fencing, which is often used for livestock. This design is usually cheaper than net-wire fencing, but requires more maintenance. The fences are made of high-tensile wire stretched to a tension of 200 to 300 pounds. The original design of electric fences for controlling predation consisted of multiple, alternately charged and grounded wires, with a charged trip wire installed just above ground level about 8 inches outside the main fence to discourage digging, but most recent designs have every wire charged. The number of wires, and spacing between them, can vary considerably among sites. A standard design uses 13 strands, but other designs have used less. Electric fencing is best used in areas of flat terrain with relatively little vegetation, and high tensile wire requires adequate bracing at corners.
Labor to keep electric fencing functional can be significant. Tension of the wires must be maintained, excessive vegetation under the fence must be removed to prevent grounding, damage from livestock and wildlife must be repaired, and the charger must be checked regularly to ensure that it is operational.
Finally, another option is to electrify an existing fence. This can be particularly effective if a net-wire fence is modified with electric wire. In this case a charged trip wire is placed 6 to 8 inches above the ground about 8 to 10 inches outside the fence. One to three additional wires may be added with variable spacing (in each case, maintaining the 8 to 10 inches away from the fence, terminating with a top wire to discouraging climbing over the fence.
If coyotes are climbing or jumping a fence, charged wires can be added to the top and at various intervals. These wires should be offset outside the fence. Fencing companies offer offset brackets to make installation relatively simple. The number of additional wires depends on the design of the original fence and the predicted habits of the predators.
The latter fence design (combination of net-wire and electric wire is currently being tested at the Ohio State University Sheep Research Center near the Wooster Campus. The sheep center maintains a flock of approximately 350 ewes for research purposes, with about half lambing in February and the other half in May. During 2006 the center lost many lambs to coyotes, which complicated research projects involving the lambs. Consequently, the sheep center built predator-proof fencing for a portion of the facility in an attempt to eliminate lamb loss for 2007. Because of the expense, the Center has electrified only a subset of available pasture, and rotates ewes with lambs accordingly. Current research involves monitoring coyote activity to determine the effectiveness of the fence design. This design will be on display at the 2007 Ohio Sheep Day.
As with all aspects of predator management, producers must consider the economic loss to predation balanced against the cost of the fence, expected life of the fence, and the relative effectiveness of the design when determining which fencing system is most suitable.