Missing White Doves

Hi all, I'm hoping someone can give me some good advice.

I've owned 4 white fantailed doves for 2 months now and everything has been great, up until today. We could only find 3 this morning so I've wandered around the neighbourhood just in case it's injured or if there's any sign of a struggle with s predator.

I opened the garage door this afternoon and there was one sitting in a box. I thought this was the missing dove, but it turns out it was one of the other 3 (I can tell by their coloured rings). It must have ventured in at some point today. Anyway, I took him outside and now I can only find 2. I really don't know what's going on. Theres plenty of food out for them. I never let this go empty. The temperature outside has dropped so I don't know if they could be somewhere trying to keep warm. I just hope they find their way back home.