I'm so sorry for your loss.
You should not be so hard on yourself. I think everyone who has had any type of poultry or birds have something like that happen at some point. I've never had chickens...just guineas, but I've lost a number of them under all different circumstances. I've had a coyote come into my yard in the middle of the day and kill guinea keets and I've had a fox come and grab them from the edge of the property when I was nearby working in the garden (my guineas free ranged during the day but were inside at night). No matter the circumstances, it's always hard and it never gets any easier! But, you can't protect them 24/7 and things happen. Don't blame yourself...just know you took the best care of her that you could. It sounds like she was very loved!
With your description of the situation, I have to wonder if some sort of bird of prey got her...like a hawk or eagle. What part of the country do you live in and have you seen any circling around your area? (My first thought would be raccoon as well, but I've rarely seen any out during daylight hours)
Btw...Although I don't enjoy looking at those types of pictures, I am more than happy to take a look and try to save your other birds from getting picked off by the same predator.
that's really sad. I live in a kind of rural arear with a couple train tracks behind my house. Thought the semi constant trains would keep animals wary.
