 This species is occasionally parasitised by the great spotted cuckoo , a brood parasite for which the Eurasian magpie is the primary host . Red @-@ billed choughs can acquire blood parasites such as Plasmodium , but a study in Spain showed that the prevalence was less than one percent , and unlikely to affect the life history and conservation of this species . These low levels of parasitism contrast with a much higher prevalence in some other passerine groups ; for example a study of thrushes in Russia showed that all the fieldfares , redwings and song thrushes sampled carried haematozoans , particularly Haemoproteus and Trypanosoma . 
