Same thing happened to me. Most were left behind, few were actually taken. I always kept a close eye on my girls but some of the attacks happened minutes after I walked away or w/ me & my dogs outside, always during the day. I looked at their bodies before burying- no blood visible, two SMALL puncture wounds on their backs above their shoulders. Dog-like animals I guess will grab, then shake, actually traumatizing the internal organs. Their bodies didn't look disheveled, like they were caught off guard then it was over. I have every kind of predator out here but bc of the size & distance of puncture marks, I'm guessing mink, weasel, fox. Something along those lines. I believe all 3 will create stashes w/ the bodies, weasels & minks sometimes just going on a spree & leaving the bodies, so I've read. With birds of prey, it's just one at a time and they're just poof, gone.