Nest secondary plants and their associations with haemosporidian blood parasites in blue tit females.

Abstract

Avian nests often contain aromatic plant fragments, which has led to propose among others that they repel ectoparasites or vectors of blood parasites (‘nest protection hypothesis’). To date, the relationship between secondary plant provisioning and the parent's blood parasites remains unexplored. We investigated whether the presence of secondary plants in nests during different reproductive stages (before incubation, during incubation and nestling period) was associated with the presence of nest-dwelling ectoparasites and females’ blood-parasite infections in blue tits () during chick rearing. In this species, females are highly exposed to parasites, particularly at the beginning of the breeding season, since they build the nest and incubate alone. They also brood the nestlings while the male assists with provisioning. We found that females that provided fewer plants before incubation were more likely to be infected by. Specifically, Females that did not provideherbs before incubation were more likely to be infected by bothand, reinforcing the ‘nest protection’ hypothesis. Thus, secondary plants may create an early environment that masks the odour of hosts or repels vectors. Surprisingly, the presence ofduring the nestling period was positively related toinfection. Given its fastest development among haemosporidians, we speculate thatherbs are provided by females to reduce mother-to-offspring transmission or as a self-medication strategy. Finally, the number of plant fragments provided before incubation was negatively associated with the number of () larvae, whereas there were no associations with the presence of mites ().