These birds are Speckled (=Rock) Pigeons Columba guinea found in rocky places, towns and cities in parts of west, central and southern Africa. For further details see relevant field guides or Roberts Birds of Southern Africa

@ Philip I actually thought so too, but the environment in the picture is a wetland and these birds are regular visitors to this place. That why i'll need comments on their ecology and habitat ranges.

Hi Azubuike. Are there any suitable places for these birds to nest in the area where you have seen them? I only have experience of this species from southern Africa where they are found in a number of different habitat types. They are common in some towns where they nest on buildings and are also present in coastal villages where they nest on buildings but often forage among the sand dunes. I have also seen them in salt marsh habitat on the Kei estuary feeding alongside waders! They even occur on islands a few km off the coast of South Africa where they breed in old buildings and fly to the mainland to feed in fields and grassland during the day. They are principally seed-eaters but also take some small fruits (Roberts 7th edition).