If you have a game camera, put it up. Most likely the predator has been around and will be back and then you will know what you're dealing with. I have several cameras and most nights when the predators roam here I see one on at least one of the cameras. We have mostly coyotes here. Nothing here prey on coyotes but the will kill most everything including bobcat and fox if they catch them. A coyote behind some of the coops recently. The date is wrong on the picture.
So sorry for your loss. It's hard when you loose birds to predators. Most bird owners have lost birds due to predators at one time or another. Everything I have done to fortify my coops and pens was due to losses from predators. Live and learn. Good luck...
Live and learn is right. I remember my second batch of chickens that I was determined to protect better than the first ones. I had them locked up tight in a secure horse stall, hardware cloth on the top section and the raccoons used the tunnel beneath that was made by a groundhog to come up under the floor. I was shocked at that one.
Recently I had an owl go right through some crappy netting. It had killed a couple of birds the night before. I put up another piece of the crappy netting up and moved those birds to another coop. I put a camera in that pen pointed towards the coop. Here is a picture of the owl going through the netting. Now I found a piece of good netting and replaced that crappy stuff but did not have enough to go across all of the pens so I bought more good netting and after this rain goes by I'm going to put it up, but I have to take the rest of the crappy netting down. I bought the crappy netting online and it wasn't what I thought it was. That owl isn't going through the new netting.
Years past I used fishing line across the top of the pens but every now and then an owl would get in and kill a bird so I bought some good netting and covered the pens but it didn't quite cover the pens totally so I bought other netting to fill in the gap and recently when that owl busted right through the crappy netting I was shocked. I have electric wire around my coops and pens and we have a lot of coyotes.