Well, I think it would fit 10 canaries quite nicely. Ten chicken hens, not so much.

The bottom measures just over 5 ft x 5 ft, and the top, including the two nest boxes, is just over 3 ft x 5 ft. It has two thick removable perches inside, and even though it's nicer than the ones at the feed store, I really think the new ones are seriously overpriced. It's made out of cedar wood. It was on Facebook Marketplace. I saw it when he had it at $500, but as soon as he lowered the price I PMed him and bought it.
Experts, please contradict me if I'm wrong, but my best guess is 3 average sized hens and a rooster would be the max in it??
I am a little concerned that something might get into it from underneath. I'm thinking of using either hardware cloth (bought some 1/4 inch for the chicken coop project) or some sort of base that keeps predators out.