Abundance and stability of populations of a chewing louse,Mulcticola macrocephalus(Phthiraptera: Philopteridae), on common nighthawks,Chordeiles minor(Caprimulgiformes: Caprimulgidae) in Manitoba, Canada

Abstract

AbstractPopulations of the chewing louse,Mulcticola macrocephalus(Kellogg) (Phthiraptera: Philopteridae), were investigated on its host the common nighthawk,Chordeiles minor(Forster) (Aves: Caprimulgiformes: Caprimulgidae), from 1992 to 2013 in southern Manitoba, Canada. The louse was present in all but one year with an annual prevalence of 0.52, mean intensity of 16 lice per infested bird, a ratio of 0.81 males and 1.89 nymphs to female (n=178). Intensity was the same in the first 11 and last nine years of the study, but prevalence dropped from 0.59 to 0.34 between the two decades. Population variability for annual abundance, measured as PV, was 0.49. In August, adults and newly fledged nighthawks had a prevalence of infestation similar to the adults that immigrated in the spring, but mean intensity did not reach spring levels until September–October. Samples of hosts were small in some years, reducing the precision of parameter estimates, particularly those based on ratios. The population parameters forM. macrocephaluson a native migrant host were intermediate in the ranges of parameters for four species of lice on non-migratory, introduced feral pigeons,Columba liviaGmelin (Aves: Columbiformes: Columbidae), but the distributions ofM.macrocephalusamong nighthawks was less severely aggregated than those from pigeons.