This is most likely a mink kill. Mink will attack during the day, and like most predators will go after weaker animals. When it happens outside of a coop, there is usually no sounds, no struggle, no feathers. They will grab them by the neck, puncturing the main artery there and sucking their blood, quickly causing delirium and incapacitation. The birds don't bleed out because of this reason, there is very little blood left unless they are interrupted. You often won't see the two puncture wounds on the neck unless you look for them. Mink and Marten are my ground predators here and I'm very familiar with how they operate. Mink are cute, but they are evil vampires. My poultry are more at risk of a deadly mink attack when free ranging than from a bald eagle attack. We have far more eagles than mink, eagles only go after my birds when they're desperate, and my birds always survive an eagle attack because the birds are too heavy to just swoop away which forces the eagle to the ground where they are quite vulnerable. Oh man, the stories I could tell you, especially one particular duck that survived 8 eagle attacks and one mink attack, that poor girl was as tough as they come.