Sorry to hear about the loss of those calves, terrible. I had just stated in another in another thread about coyotes, that we lost three heifer's calves one year, that ranged from a day to 3-4 days old. I am very certain it was coyotes, we did find the carcasses though. Last year we had about a three month old calf that had a big abrasion on her front flank, she was also sick with some sort of respiratory illness as well, not sure if she was sick and something tried to get her, or she ran and got stressed out causing pneumonia. We brought her up to the barn to treat but lost her. Lots of things can and will happen to them. When we had sheep coyotes were a major problem, eventually put me out of sheep. We lost several lambs and even 3 mature healthy Suffolk ewes. A neighbor even lost a mature Suffolk ram.
We have been worried that bears may be problems, since they have made their way around these parts the last 3-4 years. So far no issues from a bear, other than speeding up the downing of some trees and limbs. Possibly we think a bear may have been the culprit that got a lot of our tomatoes, turkeys could be suspects too though.