Have a rooster that has been separated from his hens for about a month and a half now (waiting for a couple of hens to re-grow feathers due to a feather picking hen). About a week ago we bought five 4 week old pullets and housed them in their own pen near the rooster (that is where the available shade is). At first he ignored them, then crowed and made a noise which caused them all to go running into their coop. Next day he did the same thing; they ignored him and run around playing as usual. Now he is making this EEEEEEEEEEEE noise, which sounds like a squealing noise. Do you know what that means? He is not mean or anything, it is just so odd ... he does spend a lot of time watching them so we think he enjoys doing so. Does that noise even have anything to do with the new pullets?
I know exactly what the vocal is that you're referring to. My rooster often does it quite out of the blue for no apparent reason. The hens and the chicks will all stop what they're doing and be very quiet. The silence lasts all of ten seconds and everyone is back to their noisy selves doing what they were doing previously.
My previous roos all made this noise, too, and I've never learned exactly what it means. But I'm pretty close to concluding he's just jerking my and the hens' chains. He's chuckling and saying, "Hah! Made you look!"