Some birds of different types like to live in groups. Similar food habits of some different birds might be the reason. Other reasons may be similar nesting patterns. I have observed birds like Paddy Field Pipits, Crested Larks and Ashy Crowned Sparrow Larks cohabit. One more reason seems to be that their colours match the sand of the bed creating a perfect camouflage.
One day, we found together Ashy crowned Sparrow Larks, crested Larks and pipits forage together in the Ghaggar river bed. Perhaps they are terrestrial birds. I took a photo of Juvenile Ashy Crowned Sparrow Lark ( in Front) and Paddyfield Pipit in the back in the Ghaggar River passing near Panchkula city of Haryana in India.