Warning: the video link in this blog post includes images of a sheep killed by a coyote.
This story begins several weeks back. We split our ewe flock into two breeding groups in late September, and kept a third group (of replacement ewe lambs, who won't be bred until next fall) separate. With three groups of sheep, we felt like we needed to put our youngest livestock guardian dog (10-month-old Dillon) with the lambs. He had been with a handful of lambs at our home place, and seemed to be fine - a bit exuberant (as puppies can be), but fine.
A week into this situation, we noticed that one of the lambs had a chewed ear. We've had young dogs that occasionally chewed on ears, so we weren't too worried. In the next several days, four more lambs were injured, several seriously. We decided to put Dillon with a group of older ewes and rams.
His inappropriate behavior continued - and escalated. He began chasing sheep, which culminated with a ewe that became tangled in the electronet and died. We brought Dillon home (and put a "dangle stick" on his collar to make chasing sheep uncomfortable). The older dog went back with the breeding group, and we left the ewe lambs protected only by electric fence.
Fast-forward to this week. On Wednesday, we moved the lambs to a new paddock partly enclosed by electro-net fencing, partly by hard-wire sheep fence. On Thursday morning, we found a dead lamb in the paddock.
The rancher part of me was upset - we would expect this ewe lamb to grow up to produce five or six sets of lambs. The farm advisor part of me decided that this was an educational opportunity - I wanted to learn how to tell what kind of predator had killed the lamb.
I made a quick call to our local wildlife specialist (in Placer County, these folks work for the county - in other areas, county trappers are employed by USDA Wildlife Services). He looked a a few photos and said, "That looks like a coyote." He also told me how to investigate the carcass to know for sure.
You might wonder, why would this matter? The lamb was dead. As a rancher, I wanted to know what I was dealing with! Coyotes can get through a 4x6 inch hole; mountain lions can go over most fences. Mountain lions are protected by the State of California; coyotes, at the moment, are not. As a scientist, I was inherently curious. I wanted to know the differences between coyotes and mountain lions in terms of predatory behaviors.
Our trapper told me, "A mountain lion will usually kill its prey by crushing the base of the skull from above and behind; a coyote will kill by crushing the trachea from below. A lion will not usually eat the digestive tract; a coyote will eat everything. A lion will bury what it doesn't eat; a coyote will eat in the open and leave the rest." He also told me that skinning the neck of the lamb would confirm the predator involved: "Hemmoraghing on the throat would indicate a coyote; wounds on the top of the neck at the base of the skull would suggest a mountain lion."
Fortunately, I had my hunting pack in the pack seat of my truck (including rubber gloves and a sharp knife). I skinned the neck and found lots of trauma around the trachea - and no wounds on the top of the neck. We were dealing with a coyote, as the video below indicates.
We resolved the issue (hopefully) by bringing Dillon back to guard the lambs. We left his dangle stick on with the hope that he wouldn't chase the sheep. We also moved the sheep to a new paddock that was more secure. Our landlords told me this morning that they'd heard coyotes - and Dillon barking - most of the night. And we did not lose any more lambs.
As a shepherd, the premature death of any animal feels like a failure. I hate to put a young dog in a position where we have to rely on him before he's ready; I also hate to subject our sheep to depredation. But I also recognize that there are economic considerations involved. Treating the lambs that Dillon injured earlier in the month has cost us money; losing a ewe lamb to a coyote cost us more. These kinds of trade-offs are part of ranching, I suppose; my job as a farm advisor is to help others evaluate these choices objectively.
In the next several weeks, I hope to offer a tool to help others compare the cost of using a livestock guardian dog against the benefits. Stay tuned!