Why do hens, try to mate with other hens

[HenOnTheBarn12]

ok my hen has been mating with other hens her name is strawberry she's about 3 years old and still lays she's a mix but i now she's mixed with a Rhode island red and maybe a ameracana because she lays blueish brown eggs and all my roosters were killed by the neighbors dog but my main thing is I'm still getting fertile eggs and it's been about 4 or 5 months after the roosters were killed.............

ive been researching everyday but nothing.

Im sorry for your loss! That is pretty weird though. Keep an eye out on your hens! You don't know your sweet henny could turn into a rooster.