Chew Yen Fook’s image of a Rock Pigeon’s so-called “kissing” (Columba livia) intrigued him. It shows one bird thrusting its bill deep into the gape of another (above).
What is unusual in Yen Fook’s observation is that immediately after “kissing” one bird mounted the other and copulated with it. In such a case this would be considered courtship feeding where the male offers a morsel to the female prior to copulation LINK.
The image of the ‘kissing” pair was sent to aviculturist Lee Chiu San who wrote: “Feeding is part of the courtship ritual for many species of birds. But I have never observed the feeding of crop milk between two adult pigeons or doves. However, there is always a lot of billing, cooing, and mutual grooming going on, as this photo, taken in my garden, shows.
“…yes, it does look that one bird is gaping, and the other bird is sticking its head into the mouth. Very surprisingly, I would hazard that the bird on the right, the lighter coloured one, is the male, even both birds appear adult. In rock pigeons, the males tend to have more gloss. Now comes the big question, which bird was the one that mounted? Oedipus pigeon? We learn something new all the time.”
When Chiu San was shown the mounting images, he has this to say: ” Now that I have had a better look at both birds, they both appear to be male (above, below). That complicates the discussion.
“Of course I am not able to tell the sex of both of them without a hands-on examination, but if you look at enough pigeons, you will be aware that females are overall of a finer, lighter build. The stocky build and bull neck are characteristics of male pigeons. Also, as I said earlier, males have more gloss, and both birds are glossy.
“Now, to the issue of mounting. It need not be a prelude to actual sex, but is used as a dominance display in other species of animals. When there are conflicts in the social hierarchy of tribal primates (baboons, macaques, etc.) that normally live in big groups, the victor in the dispute often mounts the loser as a sign of dominance. In another species of primate, the term “F… you!” is used as an expression to assert dominance.
“In many species of fishes (wrasses, cichlids, and even swordtails) subordinate males take on the characteristics of females so as to avoid the antagonism of the dominant males. In the case of wrasses, the subordinate fish are actually female, and only change sex to become male when the dominant male is removed.
“Now, let’s discuss the extraction of crop milk. Perhaps it could be nothing more than old-fashioned extortion by the dominant male. After all, dominant primates have a long history of doing that.”
Yen Fook last words: “Appreciate Chiu San’s invaluable comments about the possibility of a male mounting another male. Since the sexes cannot be determined from the photos, anything is possible.
“Here is an excellent footage about sex and the pigeon invaluable in the sense that they are video footages LINK. In it, it also mentions lesbianism, kissing and even females mounting males. [Note: PigeonLady12136’s comment needs amendment in that if the female sticks her head into the male’s mouth, it is the male that regurgitates food, not the female.]
“My photos were some casual pictures that I took at the Singapore Botanical Gardens earlier this year when I chanced to see what I thought was a male-female courtship.”
Conclusion by YC Wee:
“The problem here is that birdwatchers are not interested in observing and documenting a common species like the Rock Pigeon. Photographers like Yen Fook are of a different breed. We need more observations of Rock Pigeons (and examinations of the birds) to establish whether males feeds females crop milk as bribery for sex or dominant males received crop milk from other males …”
Chew Yen Fook, Lee Chiu San & YC Wee