It could mean a lot of things. Maybe they are cold?
There is an earthquake
Shaking.
Sniffing.
shaking my body
If you mean "mammals", then no; Chickens have no mammary glands, and so they are not mammals.
It means they start shaking and they cannot stop, or they shake and keep shaking repeatedly.
Means someone is shaking and dancing
Shaking My Damned Head
Tremulous-quivering or shaking slightly.
smh = "shaking my head"
shaking her butt ...
There could be various reasons why a chickens beak is black. It could be bruising from other chickens or an infection.