"Yes, Alex is an owl."
Translation:Evet, Alex bir baykuştur.
In the comments, some people say you use the dir/tur... suffixe when we state a fact or a strong conclusion, and at the same time, others write this suffix implies that the speaker is not sure! So does it mean 'He is surely an owl' or 'He is probably an owl'? This is very confusing.
In this sentence, it is more like a definition of Alex, so the speaker is sure. But this suffix can also be used in uncertainty. It depends on context. So if wanted to say 'Alex is probably an owl' just in this sentence, I would say 'Herhalde Alex bir baykuştur.' (herhalde means probably). But in a conversation, you would know what the speaker means, without additional word.