No effect of the ectoparasite Crataerina pallida on reproduction of Common Swifts Apus apus

Previous studies have failed to ascertain negative effects of the Swift Lousefly Crataerina pallida parasitism on Common Swifts Apus apus. Abundances of C. pallida were experimentally manipulated to create broods experiencing either enhanced or reduced parasitism, and host life‐history traits were examined. No significant differences in clutch and brood size, rate of growth, asymptotic and fledging mass and size, or the number of fledglings per nest were observed. Reductions in parasite virulence may have developed due to the connection of C. pallida and host success, or costs may be borne by traits not influencing immediate fledging success.