Male incubation feeding and fleas

Parasites exert a strong selection pressure on their hosts as manifested in behavioural antiparasite traits to reduce negative impacts on fitness. The numerous nest-dwelling ecto-parasites residing in avian nests make altricial birds excellent model-systems for investigating the relationship between parasites and their hosts. Here, we experimentally increased natural levels of hen fleas (Ceratophyllus gallinae) in blue tit (Cyanistes caeruleus) nests during incubation, and tested their effects on parental incubation behaviours and reproductive performance. Our experimental addition of fleas resulted in an increase in feeding effort of males to incubating females. Frequency of male feedings was also positively related to clutch size. These results suggest that males increase their reproductive effort in flea manipulated and large broods. This will, at least partly, compensate female costs in nests with high ecto-parasite density and many nestlings. Furthermore, nestling mass at day 6 in ...