Extreme Male-biased Infections of Masked Shrews by Bladder Nematodes

Intensity of parasitic infection (number of parasites per host) can vary by date, and with host age and sex. We tested whether variation in bladder nematode (Liniscus [= Capillaria] maseri) intensity in Nova Scotian masked shrews (Sorex cinereus) was related to these variables. We collected a total of 117 shrews on 8 different sampling occasions between mid-May and mid-August. Univariate relationships suggested that intensities declined between May and August, and were higher in male shrews. In analyses simultaneously testing for relationships between intensity and date, age, and sex, the most compelling pattern was strongly male-biased parasitism.