Alpine Swift (Apus melba) Science Article 5
A population of Alpine Swifts Apus melba showed the highest louse-fly parasitization rate (74%) as far as known in birds. This might be caused by a limited ability to preen. The prevalence was lower in second-year birds than in adults, probably as a result of their breeding status. Parasitization affected neither body condition, nor the probability of transmission of blood parasites. Due to mobility of louse flies, we suggest that heavy infestations have a short duration, and thus do not affect individual Swifts in terms of physical deterioration.
Tella J.L., Gortazar C., Gajon A. & Osacar J.J., ARDEA 83 (2): 435-439