I have a very tiny backyard in a densely populated suburban town. I keep 4 Aussies and currently 9 leghorn chicks though those need to go. The chooks have an 8 x 11 foot area enclosed with a 4 foot picket fence and usu their gate is open so they can run around in the back half of the yard as well. The yard is surrounded by a 6-8 ft privacy fence, but it has loose boards and spots here and there where the neighborhood cats squeeze in. They have plenty of cover from hawks and other flying predators and are locked in the very secure coop at night so I never worried much. The past few days to a week they have been very loud/excited during the day starting at dawn. I had to fetch one from a neighbors yard so I clipped wings so that would not happen again. Then for the past couple of nights they were not all going in the coop at dusk. The coop has an auto door and a webcam. We would check the cam, notice they were not roosting and then go out and round up the chickens from various places in the yard and put them in the coop. I thought maybe the presence of the chicks was throwing them all off so I brought the babies inside. Last night being Christmas we forgot to check to make sure all were in the coop before the door closed. They were happy and accounted for just 45 minutes earlier but around 5:30 we heard a commotion in the back yard. We went to the back door to investigate to find Mama chicken pecking at the back door trying to get in the house. She came in when we opened it. Nothing else seemed out of whack yet so we thought she might have stayed out looking for the chicks and so we returned them to the coop, when we found one chicken in the coop but cowering in a nest box. One chicken in the compost bin, and the last one nowhere to be found. We searched our yard and all the adjoining ones last night and this morning. There was no blood, no feathers, no remains,no unusual looking scat. Something had dug under the fence a couple of weeks prior but I had filled in the hole and it was undisturbed last night. There was a cat in the yard last night but it ran away when we opened the door and I have never thought the neighborhood cats to be a serious threat, these are full grown Australorps. Our best guess is a fox, based on the complete lack of evidence at the scene and the spooking leading up to this. I am headed out today to get the stuff to completely enclose the run. Wish I had done it before but it never occurred to me that there was a predator bright enough to prevent the chickens from entering their safe place rather than try to break in. What do you think? We are in the SF bay area. There are foxes around the area I did not think there were any in the immediate vicinity though, it is very densely populated here with no open space/wild space for a couple of miles.