Poles? Chickens do not have feet like Song birds--toes in front that curl around a branch and the back toes is reversed to hold on from the back. Chickens are like Pheasants, that are ground sleepers (although they, of course,can fly to trees.) And chickens will gladly roost in trees, too, but to make them comfortable, well balanced and keep feet warm in winter(in cold climates) their roost will be better designed--a 1x2 board.(or 1x3 for largest fowl) They can fly up without teetering for balance, can land and leave the roost board safely. In winter, they cover the feet when hunkered to sleep. A bark covered branch has great hiding places for mites, even though it is often a choice. Still, use what you like, but know that there are alternatives that can make chickens more safely roosting and comfortable.....Good luck.