Geophagy in the African Olive Pigeon Columba arquatrix

Abstract

Geophagy has been found in a number of bird species, but its adaptive functions remain much debated. Little is known about geophagy in African birds. Evidence of geophagy and its possible adaptive function was investigated in the frugivorous African Olive Pigeon Columba arquatrix (order Columbiformes, Family Columbidae, previously known as the Rameron Pigeon). Avian species showing geophagy can be broadly divided into those feeding on grit and those feeding on clay. Evidence from the crop and ventriculus contents showed that C. arquatrix eat clay, and have grit in the ventriculus. The pH of the crop and ventriculus was significantly higher if clay had been digested. Birds were observed feeding on damp clay soil throughout the year, sometimes in large aggregations (50–180 birds). Birds usually fed 3–4h after sunrise and 2h before sunset. The composition of the clay ingested by C. arquatrix suggests that the birds were obtaining salts and trace elements. It appears, however, that geophagy in terms of clay ingestion in C. arquatrix has several functions, including a buffering capacity. The function of geophagy may also be to negate or absorb the effects of secondary compounds found in the fruit eaten.

Ostrich 2006, 77(1&2): 40–44