Abandoned Chickens and my worst nightmare for them

I placed this as NSFW bc it involves the death of a chicken.

I just need to vent... I'm so sad.

History

Around October, some asshole abandoned an entire flock of chickens near our house. The chickens took up residence around the neighborhood, spending nights in trees and days in our yards. Initially, I did not clock that they were abandoned.... I thought they were just adventurous with a poor excuse of an owner not keeping them properly. I did not understand they were alone until I saw them retreat into my own trees. That's when I contacted animal services...

At the time, there were around 9 chickens, 2 of them roosters. I put out feed for them in one location to try to help keep them in a predictable area. The city managed to catch 4 before they gave up the case. And I don't blame the city for giving up; these chickens are fast and agile. But how dare someone just leave them like this????

Anyway. Since it became accepted here that they would just be the neighborhood chickens, similar to the insane amount of stray cats in our area, I accepted one day, I would likely be the one to find them dead when they die of natural or otherwise causes. (They really like our evergreen trees.) I do not have the resources to care for these guys, but I do watch over them. I count myself as a "chicken lady" vs all the other "cat ladies" on our street. I have even spoken with my dog's vet about these little ones. She is equally as upset at their abandonment.

They are a resilient, dedicated, and loyal bunch. There is 1 rooster and 4 chickens now. 2 of the chickens are black, 2 are tan. The tan ones would come up to me when I used to feed them... it was so sweet. I never pet them, and I stopped feeding them when the city gave up. They graze and are healthy on their own.

Today:

Anyway... Today, a chicken found her way into my yard severely injured. She was the smallest and sweetest.

I saw her from my window in my backyard for the first time in a month. She couldn't walk straight. Couldn't fly. She couldn't lift her head. It was obvious she'd been attacked by something around the neck. I could see it clearly from inside before I rushed to her. Once I was with her, it was evident she also had a serious head injury; it was not scabbed or bleeding, but it was a goopy black. For every step she tried to take forward, she would take several backwards. She was also swarmed with flies, which she would peck at periodically to no avail. Her state was grim.

I tried to give her water, and she was so thirsty... she tried to drink, but couldn't reach the water no matter how she tried and how i tried to help her.

So I found an exotic er vet to take her to, and they were wonderful given the situation. I spent about an hour in the yard with her before I collected her into a carrier. During that time, she would come to me every so often, eventually sitting beneath me in my chair. She had the most curious brown eyes.

She let me place her in the carrier without any hesitation, and i was devastated to see how she relaxed immediately upon being inside... She'd been alone for so long. She hadn't felt safe enough to rest in idk how long.

This little girl trusted me enough to know she would be safe at my house and with me to pass. I'm honored to be a safe space, but I'm also incredibly angry. I just cannot fathom doing this to any animal, much less so many.

I know I did the right thing for her, keeping her company and giving her a peaceful death.. I stayed with her till they put her to sleep. She seemed to take comfort in my presence, and I didn't want her to be alone.. and she's not my chicken, never was. But goddammit. Watching this happen and knowing it's only a matter of time for the others... idk what to do. I feel powerless.

Thanks for letting me vent. I am open to suggestions on how I could capture the remaining flock, but I have tried many strategies over the months. None have been successful.