Thanks, I had not seen that article or the German study it referenced. It was an interesting read. I could not find that study but I'll admit I did not search really hard. Maybe someone else more diligent would have better results.
The results of a study like this will depend on the...
If you read this experiment you'll see that they don't care if the roosts are flat, round, narrow, or wide. People do but chickens don't.
Perch Experiment
https://www.backyardchickens.com/articles/the-perch-experiment.74272/
If you look at this photo you'll see that the can actually grip...