Chickens

Foxes?

 

Normally foxs

 

Owls will do this.
sorry for your loss.
Sorry i reread your post and saw there were more than one loss, i would say weasel.

 

Weasel. Hard to catch (for me) but it will continue killing until it is stopped. Look around for it's nesting area. They usually stay close to their food supply. In the daytime you will probably find it asleep.

 

You need to identify this killer. Shore-up your coop but, if you don't know for a fact what predator you are dealing with, you will stay at a disadvantage.

Game cams are now relatively inexpensive.

Using this set-up will alarm you to any movement near your chickens.

Buy the cheap motion detector double security lights. http://www.homedepot.com/h_d1/N-5yc...&keyword=motion+detector+lights&storeId=10051

There are more expensive motion detectors. I'm assuming they are probably better at detecting movement. You may want to spend the extra money on better detection. I got the cheaper ones and don't regret it. YET!!

Point the detector in the direction the predator has been travelling. Instead of a bulb in one of the sockets, screw in one of these receptacles that you can plug a cord into.http://www.amazon.com/Leviton-125-2-Pole-2-Wire-Adapter/dp/B001PCVTFC/ref=sr_1_2?ie=UTF8&qid=1353891411&sr=8-2&keywords=light+bulb+socket+outlet

With one of these you would be able to have the light and cord also. http://www.amazon.com/Leviton-1403-Outlet-Socket-Adapter/dp/B001F71O70/ref=sr_1_1?ie=UTF8&qid=1353891411&sr=8-1&keywords=light+bulb+socket+outlet

Run the cord into the house to a buzzer or radio. Here is a buzzer. http://www.buzzersdirect.com/produc...-buzzerbr-part-number-12pn31100-ul-recognized

When the motion detector sets off the "alarm", you go out and either kill this thing or at least identify it. The other light in the fixture will provide you with enough light to see what you're doing.

 

I once had a raccoon that did this till we eliminated it. Good luck!