Maron, M. W., N. Paprocki, J. P. Owen, and C. J. Conway. 2024. Differential effects of chewing lice on body condition across host age and sex in Rough-legged Hawks (Buteo lagopus). Journal of Wildlife Diseases 60:in press.
Abstract
Chewing lice infesting avian hosts can significantly affect host health and fitness. Here, we present quantitative data on host body condition and louse abundance observed from 121 Rough-legged Hawks sampled across their North American nonbreeding range. Among hawks examined, louse prevalence was 71% with a mean abundance and intensity of 9.1 and 12.8 lice, respectively. We identified lice as Craspedorrhynchus ssp. and comment on potential for taxonomic revision. Female and juvenile hawks had greater louse intensity and prevalence compared to male and adult hawks, respectively. Host body condition, measured as a breast muscle score (keel score), was negatively correlated with louse abundance after controlling for host age and sex. We discuss the hypotheses that may explain these patterns, including sex-biased louse transfer between adults and nestlings, body size differences between males and females, and preening limitations in females and juveniles. Our results corroborate previous studies suggesting the primary sources of intraspecific variation in louse abundance are host body size and preening limitations.