I recently moved to a small farm and became the owner of 7 chickens. I was ASSURED by the previous owner that they are all hens. One of them is definitely crowing every morning, starting at about 5 a.m. So do hens ever crow, or do I have a rooster in disguise?

The neighbors have made it clear that the crowing is not appreciated, so she/he needs a new home. This confused chicken is free to anyone who wants him/her. I'm not sure of the breed, but it looks like the stereotypical rooster pictures that most layperson books contain. Please help!