I checked with one of the Illinois Department of Natural Resources district wildlife biologists about this. Here is his response: Were there holes in the lambs' craniums? Eagles (and probably hawks and owls, too) will grab at head and the body. I had a turkey decoy grabbed by a Red-tailed hawk (Yes!) while I was turkey hunting. He carried it off and then dropped it. When I retrieved the decoy, I saw three (four?) talon marks/holes in the decoy's head/neck, while the body of the decoy had the other set. IF it's an eagle, it would most likely be a Golden eagle rather than a Bald eagle. Though they do occur in Illinois, and would assume along the Mississippi River, golden eagles are rather uncommon visitors from the western plains states. Eagles will "skin out" its prey as it eats. Ribs are often clipped off near the backbone. Other possible predators include hawks, coyote, bobcat, red fox, gray fox, and even raccoons. It could also be a free-ranging dog, a not uncommon culprit in these types of situations.
The dead lambs should be skinned out to look for any puncture wounds, where they are on the body, and to measure the spacing and shape of such holes. If it was a ground predator, you'd think you'd find tracks somewhere . . . with all the rain, even in pastured/grass-covered areas. The landowner should check the fences surrounding the pasture for signs of critters entering the area . . . most likely under a fence. Research has shown that good maintenance of fences prevents a vast majority of coyote depredations. Also, if it's a ground predator, entry/exit spots provide a trapper good locations to use traps or, better, snares (if legal . . . check with Conservation Police Officer first). No matter what predator was involved, keeping the ewes and lambs up closer to the buildings, sheds, etc. until the lambs are larger will help. Use some sort of shepherd or flock dog (i.e., guard dog) to keep predators at bay. Supposedly, llamas work well to keep away coyotes.
He also suggested that you check out: Prevention and Control of Wildlife Damage. Editors, Scott E. Hygnstrom, Robert M. Timm, Gary E. Larson. 1994. University of Nebraska-Lincoln. 2 vols. (http://digitalcommons.unl.edu/icwdmhandbook/ [chapters and access to them pdf-wise]) Here are three chapters from that resource that might be particularly useful: http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1059&context=icwdmhandbook (Eagles http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1001&context=icwdmhandbook (IDing damage) http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1061&context=icwdmhandbook (Hawks and Owls)
