doves being eaten

I live in a wooded area in Texas. I had about 20 doves that were regular to the area near my house. In the last few months something has eaten all but two of them. I find piles of feathers and nothing else. Whatever it is seems to only take the doves, and always eats them or picks them clean in the same area in the woods. The two doves that are left have decided that the place they want to stay is the trees closest to my house and under a light. I have looked for owl pellets but have not found any close by the feeding area. I have not been able to find any bones and only once was there any blood on the pile of feathers on the ground. Please help me find the answer if possible. Thank you in advance. April