My young guineas can and do fly very well. It's not uncommon for them to be on the roof of the buildings. My young ones right now are 2 and 3 months old. But at this age mine are usually walking when they are exploring their territory. They may not free range too far from their 'safe' area until the following spring. My adults will range all over 30 to 40 acres but the young ones stay close to the buildings for the 1st year. The only time I see them fly is when the adults are chasing them or they get scared by something. 
