I figured another chicken killed the first chicken. That is why we separated her from the rest of the flock. Unfortunately this little one didn't make it through the night. Thanks for your responses.
We recently had our first batch of chicks hatch (incubated by their mother). The first one to hatch had holes pecked in its head and died shortly after. So we separated the rest of the chickens from broody momma and her eggs. The next 2 are healthy and doing fine. The forth was injured when we...