Hee hee. I could have told you they were roosters had I seen that photo. You could have too... had you been learning stuff at http://www.backyardchickens.com. You can figure out the sex sometimes as early as 4 weeks old. (We've had our own adventures in figuring out gender you see.) There's even a section at backyard chicken just for this sort of thing. Next time you get chickens.. post a photo in the breed and gender message board and ask the chicken gurus what they think. Here's an example of the one's I've asked:

http://www.backyardchickens.com/forum/viewtopic.php?id=104836

Here's another one:

http://www.backyardchickens.com/forum/viewtopic.php?id=116420

They've been right every time. :D