I classify feral dogs & loose country family dogs as part of the predators in myy area. ANY Farm barn, pen/paddock I build, must keep out ALL predators for that farm animal... from hawks, ravens & owls overhead to canines wild or domestic like weasels, foxes, dogs, coyotes, wolf hubs turned...
5 claw-marks in all your pictures... rules OUT feral Dogs, Coyote, Wolf & by size, rules out Fox or Weasle. That leaves front-foot, 5-clawed families of predators:
Bear/Wolverine very possible. Racoon & Martin aren't likely from 3+inches wide clawmarks.
Cat family: Bobcat/Cougar. You don't...
What is your protein source in your feed?
Wheat alone & fruit isn't a complete protein at all, even with the yogurt. Perhaps your wheat feed has some source of protein added to the wheat?
I'd sure get some mealworms or a prepared layer feed into your birds.
Also, you are describing what sounds...
Baby ducks can't swim!
Wet baby ducks are like wet baby chicks- they get cold & croak. Use a chick waterer for at least the first 2-3 weeks while they are only wearing baby fluff & haven't to their real feathers. Their water can start out a chick waterer, but as they reach 3-4 weeks, they'll...
That darker mat of bedding in the center? You had an egg break some time along & mama probably tossed out the shell pieces as she turned & moved the other eggs. Now, its rotted your bedding.
Your other eggs, while soiled from mama moving & turning them about, may still be living. Candle them...
Chicken wire isn't strong enough to keep out much over the strength of a weasel. Coyote, feral dogs, skunk & coon can all Rip up chicken wire with their mouths & feet. I use graduated pig fence( rigid wire panels) from the Feedstore that are about 6x16 foot. Bigger cost investment but going on...
Toes curled-up on the injured leg? That sounds like birth defect - like clubfoot. Nerve damage or birth defect...
Vet or...
Try this:
1. House by self for medicating in its h20:
1. Sugared electrolyte soln. added to its water.
2. Shave a bit of a human Calcium tablet into its water. Not a whole...
If it is in line or appears in shape, then I would suggest you treat for "splay-leg". Some chicks' will have legs too weak to properly stand so they sort of say out sideways so it appears the chick is sitting on its rump. You can give it the support it needs with a itty bitty hobble that you...