Mike Tan’s (a.k.a. woof) documentation of the courtship of the Spotted Dove (Streptopelia chinensis) shows the pair indulging in allopreening of the head area (above). Note that the eyes of both are covered with the nictitating membrane, although in another image not shown here, one bird has its eyes open.
The stage of the courtship documented here is apparently advanced, probably missing earlier display of head bowing, etc. This is confirmed as immediately after, the female crouched and the male jumped on her back (left).
With the female standing on firm ground, there is no problem about losing her balance as when on a perch. Even then, her wings are somewhat stretched to provide balance. The male on the other hand has a harder time balancing himself with his wings as his tail maneuvers beneath hers to effect the classic cloacal kiss. Note that his body feathers are all fluffed.
This post is a cooperative effort between NaturePixels.org and BESG to bring the study of bird behaviour through photography to a wider audience.
Images by Mike Tan.