APPARENT LACK OF EFFECTS OF A HIGH LOUSE-FLY INFESTATION (DIPTERA, HIPPOBOSCIDAE) ON ADULT COLONIAL ALPINE SWIFTS

A population of Alpine Swifts (Apus melba) showed the highest louse-fl y parasitization rate (74%) as far as known in birds. This might be ca used by a limited ability to preen. The prevalence was lower in second -year birds than in adults, probably as a result of their breeding sta tus. Parasitization affected neither body condition, nor the probabili ty of trans mission of blood parasites. Due to mobility of louse flies , we suggest that heavy infestations have a short duration, and thus d o not affect individual Swifts in terms of physical deterioration.