I'm sorry for your loss, you sure can get attached to them.
How much many sqft are your coop/run?
Acting scared and huddled in the corner, I would be more inclined to try to figure out what scared them. Hawk, stray dog coming through, predator (rat, possum/raccoon/fox/coyote, etc.). Setting up a game cam may reveal something lurking.
Birds that are startled/frightened can fly into to walls/fencing and break their neck or even suffer from heart failure.
I have seen pecking order spats with my hens and they can be nasty with one another, but I've never known a bird to suffer from a fight or spat that didn't have a mark on them. I feel that you would have seen blood, torn skin (including comb/wattles) and lots of feathers too.
I have had a rooster try to kill hens and that was brutal - you will see evidence of birds attacking one another.
All that said, I'm very sorry that you've had to experience a loss so early on in chicken keeping. I think they are some of the most lovely creatures on earth and I adore mine, but sadly, sometimes things happen beyond our control and sometimes we may make a mistake - but we learn from it, try to make changes when necessary and move forward. All of us have bad moments, but you can't let that paralyze you and keep you from enjoying the rest of the flock and watching them grow and flourish.
Just my 2¢
I appreciate the feedback, thank you. I used to seriously hate chickens, bad experiences as a child. With times the way they are, we decided to give it a go, and I fell in love with them. Who knew these birds would change me as a person, for the better?
Goldy (Roo) was her buddy, protector, food pal, she tucked her head under him to nap and sleep. Pearl is clearly our alpha pullet, make no mistake. She would peck Ladyhawk when she thought Goldy wasn't looking, but Lady would squawk and Goldy would put Pearl back in her place.
I had been told on these forums he would need to be removed when he started trying to mate, this was misinformation. They all grew up together, same age, same size.
She had a stress triggered heart attack, flopped around like a fish and died, which probably scared the other 3 pullets.
The vet did discover areas with drying blood that we didn't see in the dark, she had been battered by the alpha. The alpha suddenly took on behavior of trying to hide, and the others accommodated her in a group in the corner. I honestly feel she knows what she did, she has run from me today each time I've went to check on them. I've not changed my behavior towards her, that won't do any good if I did.
She's always been a bully, Goldy was always Ladys protector, I messed up.
