HEMATOZOA OF FERAL ROCK DOVES AND ROCK PIGEONS IN MIXED FLOCKS

Large numbers of feral rock doves (feral pigeons) Columba livia and ro ck pigeons C. guinea fly daily in mixed flocks between roosting and ne sting sites in Cape Town, South Africa, and feeding sites in farmlands north of the city during the austral summer. We examined blood smears for haematozoa from 33 feral pigeons and 50 rock pigeons collected du ring the summers of 1991/1992 and 1992/1993 in the south-western Cape, and from nine rock pigeons collected during May 1992 in the north-eas tern Cape. Haemoproteus columbae was the commonest of three parasites recorded. Leucocytozoon marchouxi and microfilariae were recorded in a male feral pigeon from the south-western Cape and a male rock pigeon from the Stormberg, respectively. The prevalence of infection by H. co lumbae was sex biased (higher in females) only in feral pigeons, and w as significantly higher in feral pigeons (73%) than in rock pigeons (1 2%). The mean intensity of infection by H. columbae was independent of host-sex and was not significantly different between years for both h ost species. Overall mean burdens of this parasite were significantly higher in feral pigeons (xBAR = 145; SD = 398; range = 0 - 2190; n = 3 3) than in rock pigeons (xBAR = 1; SD = 3; range 0 - 12; n = 50). The mean burden in infected feral pigeons (xBAR = 199,1; SD = 456,8; n = 2 4) was significantly higher than that for infected rock pigeons (xBAR = 8,0; SD = 2,5; n = 6). An explanation for significantly higher infec tion by H. columbae in feral pigeons than in rock pigeons in the south -western Cape might be related to nest site locations and availability .