Inca Doves are only about 8 inches long. You can see how small this little dove is compared with the Mourning Dove beside it, which, at 12 inches, is still relatively small.
"The Inca Dove engages in an odd behavior, known as "pyramid roosting." Pairs or groups of Inca Doves may huddle together in the sunshine, with some sitting on the back of the others. The pyramid may be three layers high and include up to 12 birds."I saw this behaviour last week. Three doves were playing and digging in the dirt in a driveway across the street, after which they huddled with one bird on top of the other two for about twenty minutes.
-- from Inca Doves, Cool Facts, Cornell Ornithology Lab's "All About Birds"