What type they are would be easier for breed experts to hazard a guess at if they knew what color they are, and all other descriptive points you can offer.
Personal guess is that they are roosters, and of a fighting breed like Games, and they're tethered so they don't kill each other. There are almost guaranteed to be hens there but they would likely be left freerange... But that's all just guesstimating based on how I've seen some people tether chickens.
They possibly don't have coops because they are so aggressive they're not as likely to fall prey to the average predator as most chooks are, or maybe the owner doesn't believe in coops. Plenty of birds cope fine running loose. Tethered is another issue but maybe he has some other security measures in place like dogs on patrol.