Marked dietary differences between sympatric feral rock doves and rock pigeons

Abstract

Although feral rock doves Columba Iivia and rock pigeons C. guinea fly daily in mixed flocks between roosting and nesting sites in Cape Town, South Africa, they feed separately in farmlands north of the city during the austral summer. Examination of the crop contents of 32 feral rock doves and 48 rock pigeons revealed that 28 (88%) of the feral rock doves had fed on processed cereals, whereas all 48 (100%) of the rock pigeons had eaten whole wheat. The processed cereals were obtained from dairy cattle feedlots, whereas the whole wheat is waste, found within the stubble. There is equal nutrhional advantage from feeding on both food types, and feral rock doves have no apparent preference for either food type. This d'ferential feeding behaviour suggests resource partitioning. and that introduced feral rock doves do not displace indigenous rock pigeons from summer food sources in the southwestern Cape Province. Alhoewel tuinduiwe Columba fivia en kransduiwe C. guinea daagliks in gemengde trappe vlieg tussen slaap-en broeiplekke in Kaapstad, Suid-Afrika, en plase noord van die stad gedurende die suidelike somer, vreet hulle in aparte lokaliteite op hierdie plase. 'n Ondersoek na die kropinhoud van 32 wilde tuinduiwe en 48 kransduiwe het aan die lig gebring dat 28 (88 0 /0) van die wilde tuinduiwe verwerkte graangewasse gevreet het teenoor die 48 (100%) kransduiwe wat heelkoring gevreet het. Die verwerkte graankosse word verkry vanaf melkbeeste se voerkrale, terwyl die heelkoring afval is wat in die stoppellande gevind word. Die voedings-waarde van die twee kostipes verskil nie, en die wilde tuinduiwe toon geen oenskynlike voorkeur vir enige van die kostipes nie. Hierdie eiesoortige vreetgedrag dui daarop dat hulpbronverdeling plaasvind, en dat die uitheemse tuinduiwe nie die inheemse kransduiwe verplaas van hulle somer voedselbronne in die suidweste-like Kaapprovinsie nie.