A rule od thumb for doves ..... 2 square feet per dove . 6 x 3 x 6x is plenty of room for your doves .
I have had doves for many years . I enjoyed having my doves . I started out with a foundlling in my back yard and ended up with over ten , a rat snake got into my dove house , ate all my eggs , chicks , and my breeder set , before I even knew it was there . I lost 7 birds that night , the snake didn't even eat them all , It killed 4 and left them in the bottom of the cage ,or my poor birds died of fright .
My last dove snowy died early this summer of old age , she was 12 years old . I miss having my doves and plan on getting more soon .
If you have any questions let me know , I would be happy to share any info with you . Mine were ringneck doves. Kate
I posted a link for you on the laughing dove .
Edit :
Male and female doves look the same .
http://en.wikipedia.org/wiki/Laughing_Dove
If you do not know your doves age , you might want to check with the original owner to find out how long he or she had them , when they were bought and at what age they were when bought . This will give you a time line to guess their aprox. age .
The nest box should be big enough for your dove to turn 360 * a plastic milk jug with the front cut out , a wicker basket , or a card board box will do . The walls don't need to be high , about 3 to 4 inches deep , or even enough to keep the egg from rolling out 2 to 3 inches . Hay or dry grass , small twigs , for nesting materal .
http://www.honoluluzoo.org/Laughing_Dove.htm