Over the last 12 months, I've posted several essays about our commitment to - and experience with - nonlethal predator protection tools. Livestock guardian animals (mostly dogs, but also llamas) have been the cornerstone of our system. Several recent losses have reinforced my belief that dogs are the best livestock protection tool available.
In late September, we brought 6 ewe lambs home to use for training our border collies. They joined one of our bottle-raised lambs, an older ewe, and our llama. Sometime in mid October, one of these ewe lambs simply disappeared. On Sunday afternoon, she was there - by midweek, she was gone. At that point, we started night-penning the sheep to make sure they were safe.
Also in late September, we took sheep to some friends' pasture just north of our home place. They had raised sheep, and told us they'd put their llama with the ewe lambs and cull ewes to provide some protection. Unfortunately, this didn't happen - and yesterday, we learned that we'd lost 3 ewe lambs in the last 5 weeks. The llama went in with the sheep.
As a backdrop to all of this, I'm currently completing a master's degree in integrated resource management at Colorado State University. This semester, I'm taking a course on livestock-wildlife conflict. And my professional paper is focused on non-lethal predator protection tools. I've been reviewing a number of research papers about livestock guardian dogs and llamas.
From a practical standpoint, llamas require less extra management and expense - after all, they thrive on a diet identical to that of sheep. However, as our own experience supports, llamas are not as effective as dogs. I think there are several reasons for this.
First, I think llamas are effective in North America largely because our predators have never seen them in the wild. I joke that llamas look like they were invented by Dr. Seuss - they look like they were created by a committee! Humor aside, llamas do look, act, and even smell different from any animal I've been around. I suspect that coyotes feel the same as I do. However, much of the literature I've reviewed suggests that once predators become habituated to a specific deterrent, the deterrent loses its effectiveness.
Some of the guardian llamas I've seen and used have exhibited some degree of aggression toward dogs; others have not. Our county trapper has told me that he's seen llamas that have been killed by mountain lions. Based on these observations, I suspect that some predators become habituated to llamas - which reduces (or eliminates) their effectiveness as guardian animals. Fundamentally, as herbivores, llamas are prey animals that have (in some cases) developed protective behaviors.
On the other hand, dogs seem to be far better guardian animals (at least in my experience). While there are certainly trade-offs involved in using dogs (they have to be fed everyday, for one thing), they seem to be much more effective. I suspect that this success is due, at least in part, to the fact that guardian dogs effectively replace canine predators (and perhaps feline and ursine predators, as well) in our environment. Dogs fill the carnivore niche - unlike coyotes, mountain lions and bears, they typically don't eat sheep. Based on our experience, I'd much prefer to have a carnivore protecting my sheep than another herbivore!
In addition to using dogs, we use portable electric fencing - and we move our sheep frequently. The 3 ewe lambs we recently lost were in a hard-wire fence - and they'd been in this relatively large pasture for nearly 5 weeks. The combination of electric fence and regular movement probably helps confound the predators in our environment. The fact that we're out feeding the dogs everyday means there's a human present with the sheep regularly.
I realize that this is all speculation on my part. Scientific research regarding the efficacy and cost-effectiveness of non-lethal tools is challenging for a variety of reasons. Researchers find manipulation of predator
prevention systems problematic, and experimental design (replication and
control) can be demanding if not impossible (Fascione et al, ed. 2004). Furthermore, experimental controls that
compare the use of non-lethal tools with lack of use exposes these control
groups of livestock to potential predation, raising ethical concerns. Consequently, much of the current science
regarding non-lethal predator controls in a livestock production setting is
observational in nature.
Similarly, the economics of using guardian dogs (or any other non-lethal tool) are difficult to analyze. I know the direct cost of using dogs in our operation (approximately $300/year/dog), but I don't know how many sheep losses the dogs prevent. In other words, I can only determine the cost portion of a cost-benefit analysis.
Ultimately, I suppose this reinforces my belief that raising sheep is both an art and a science!