As of the late 1700s ( or early 1800s), this order was only represented by pigeons and doves. Prior to sea exploration there was an additional family within the order: the family Raphidae, which consisted of the dodo and two species of solitaires, all of which were found on islands in the Indian Ocean.

Once sea exploration took off, these birds were driven to extinction by over-hunting and the introduction of both predators and competitors on the islands.

I was amazed to find out that the mourning dove was related to the dodo (which probably was only the size of a large turkey).

There are now approximately a little over 300 species of pigeons (or doves) within the single family of Columbidae and they have basically a cosmopolitan distribution (though absent from the Arctic regions, Antarctica, and some islands).

Anywhere between five and ten species of pigeon/dove have also gone extinct since the 1600s, with the best example being that of the passenger pigeon that had been found throughout North America.

Several species are also listed as endangered.

There are two very unique ‘traits’ that set these birds apart:

They produce and feed their young ‘pigeon milk’ (a nutrient dense secretion from their crop). This ‘milk’ has been shown to have similar composition to mammalian milk & is also induced by prolactin (a hormone that is secreted by the pituitary gland). But both males and females can produce the ‘pigeon milk’

They also can drink water ‘continuously’ with the help of their esophagus constantly contracting as they ‘suck’ up the water. This differs from other birds that take a drink, and then tip their heads back to swallow.

Photography goals: manage to get a picture of a species on each continent and the rock pigeon/feral pigeon/domesticated pigeon doesn’t count.

Reference: https://www.britannica.com/animal/columbiform