Haematozoa of feral rock doves and rock pigeons in mixed flocks

Large numbers of feral rock doves (feral pigeons) Columba livia and rock pigeons C. guinea fly daily in mixed flocks between roosting and nesting 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 during 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-eastern 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. columbae was sex biased (higher in females) only in feral pigeons, and was significantly higher in feral pigeons (73%) than in rock pigeons (12%). The mean intensity of infection by H. columbae was independent of host-sex and was not significantly different between years for both host species. Overall mean burdens of this parasite were significantly higher in feral pigeons (x = 145; SD = 398; range = 0 - 2190; n = 33) than in rock pigeons (x = 1; SD = 3; range 0 - 12; n = 50). The mean burden in infected feral pigeons (x = 199,1; SD = 456,8; n = 24) was significantly higher than that for infected rock pigeons (x = 8,0; SD = 2,5; n = 6). An explanation for significantly higher infection by H. columbae in feral pigeons than in rock pigeons in the south-western Cape might be related to nest site locations and availability. Groot getalle tuinduiwe Columba livia en kransduiwe C. guinea vlieg daagliks in gemengde groepe tussen hul slaapplekke en neste in Kaapstad, Suid-Afrika, en hul voedingsareas op plase aan die noorde kant van die stad gedurende die somer. Bloedsmere van 33 tuinduiwe en 50 kransduiwe wat gedurende die 1991 / 1992 en 1992 / 1993 somer maande in die suidwestelike Kaap versamel is, en 'n verdere nege kransduiwe wat gedurende Mei 1992 in die noordoostelike Kaap versamel is, is ondersoek vir bloedparasiete. Haemoproteus columbae was die mees algemene parasiet van die drie tipes parasiete aangeteken. Leucocytozoon marchouxi en microfilariae is aangeteken in 'n tuinduif in die suidwestelike Kaap en 'n kransduif in die noordoostelike Kaap, onderskeidelik. Die voorkoms van die H. columbae infeksie was hoer in wyfies in die tuinduif en in die geheel was die infeksie betekenisvol hoer in tuinduiwe (73%) teenoor kransduiwe (12%). Die gemiddelde infeksie intensiteit van H. columbae is onafhanklik van die geslag van die gasheer en daar is geen betekenisvolle verskille tussen die jare vir enige van die duif species nie. Die totale parasiet lading van tuinduiwe is betekenisvol hoer (x = 145; SD = 398; reikwyte = 0 - 2190; n = 33) as die van kransduiwe (x = 1; SD = 3; reikwyte = 0 - 12; n = 50). Die gemiddelde lading in besmette tuinduiwe (x = 199,1; SD = 456,8; n = 24) is betekenisvol hoer as die van kransduiwe (x = 8,0; SD = 2,5; n = 6). 'n Verduideliking vir die beduidende hoer infeksie deur H. columbae in tuinduiwe as in kransduiwe kan in verband gebring word met nes plasing en beskikbaarheid.