Two are 6 months old (neither crowing yet, both silent in fact), three are just over 5 months (Visby croaks first thing in the morning, the other two have that sort of squeak between a cheep and a bawk, but Lulea's close to crowing I think), and three are one week younger (of them, only Merioneth yet crowing, the other two squeak). So same sort of age that you expect them to start crowing.May I ask how old the cockerels there are right now?
yes, though RJF are just bantam sized aren't they?I find it highly unlikely that a “beware” crow from a red junglefowl rooster would mean much to many predators found in the same jungles; the crow definitely has multiple purposes.

I'm sure you're right that crowing serves multiple purposes.