He's probably a rooster. I have one that looks very similar to yours. My kids gave me this "hen" to replace the rooster we had to rehome. We all believed he was a hen because he had a small comb and didn't have the same body as the rooster we had previously. Then he crowed and after that his comb got huge! He now sleeps in the house at night and crows inside in the morning. That seemed to do the trick until recently he started crowing during the day too. We just tried the rooster collar today. I don't know if it's working yet or not because he's too busy trying to get it off and hasn't attempted to crow. We all really like him (he lived in the house with us for a month and followed the dogs around, so we're all bonded with him) so we're trying everything to keep him and not alert the neighbors. He went from being Sheba to now being Maverick.
Here's a picture of him when we thought he was a hen:
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And here's a pic of him after he started crowing:
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