Can you spot the odd one out chicken in the picture below?

Spot the odd one out chicken Riddle

Chicken-8

Explanation:
Let's start with distinct features

Chicken-2 has an extra toe.
Chicken-3 has fewer tail feathers.
Chicken-5 has only one thigh crease.
Chicken-6 has an extra feather around the neck.
Chicken-7 is looking up.
Chicken-8 has a longer butt crease.

But this riddle is not about the features. The different chicken is 8 as cannot be seen by any chicken.