I've never actually seen a rat, but their little bills and feet were chewed off and then my husband found the tunnel. We tore everything open so there wasn't such a protected path to the henhouse and haven't had any problems since.
They do have different voices, but I haven't heard that raspy...
I had 11 ducklings from Holderreads, 6 females and 5 males (I thought from bill color upon arrival) but a rat killed most of them. I have five survivors and am trying to figure out the sex. I thought I had two males (the smaller ones) due to the darkening of the necks, but the bills seem a lot...