Anatomy and physiology

Anatomy and physiology
Overall, the anatomy of Columbidae is characterized by short legs, short bills with a fleshy cere, and small heads on large, compact bodies.[37] Like some other birds, the Columbidae have no gall bladders.[38] Some medieval naturalists concluded they have no bile (gall), which in the medieval theory of the four humours explained the allegedly sweet disposition of doves.[39] In fact, however, they do have bile (as Aristotle had earlier realized), which is secreted directly into the gut.[40]

A landing collared dove (Streptopelia decaocto) displays the contour and flight feathers of its wings.
The wings are large, and have eleven primary feathers;[41] pigeons have strong wing muscles (wing muscles comprise 31–44% of their body weight[42]) and are among the strongest fliers of all birds.[41]

In a series of experiments in 1975 by Dr. Mark B. Friedman, using doves, their characteristic head bobbing was shown to be due to their natural desire to keep their vision constant.[43] It was shown yet again in a 1978 experiment by Dr. Barrie J. Frost, in which pigeons were placed on treadmills; it was observed that they did not bob their heads, as their surroundings were constant.[44]