It could very well be a preditor has disrupted the Cote, this will cause your Doves to feel a sense of un-safe, then hiding, your dove has found new friends and very well may stay there with them.
You mention Doves, are these actual white Doves or White Pigeons, I ask this because for the most part Pigeons and Doves do not fair well together, although there are from the same family Doves & Pigeons don't get along by nature.
I am a keeper of many birds here, Pigeons, Doves, Exotics as I am a Rescue & Rehab person, my Pigeons attack my Doves when they can so I keep them seperated.
You can bring your dove home, you will need 2 cages, one small to put one of your other doves into, then place that cage and dove into a larger cage and leave the door open on the larger cage, soon the dove should go down and will go into the cage to be with the other dove, then all you would need to do is close the door and bring both back to the Cote.
Good Luck, maybe you could come over and join my group, go to yahoo, click on groups and type in Pigeon World in the search box and join my group dedicated to helping the Pigeon/Dove.
Take Care.
BrokenWing