Infestation parameters for chewing lice (Phthiraptera: Amblycera, Ischnocera) infesting owls (Aves: Strigidae, Tytonidae) in Manitoba, Canada

Eleven of the 12 species of owls (Aves: Strigidae, Tytonidae) known to occur in Manitoba, Canada, were examined for chewing lice (Phthiraptera: Amblycera, Ischnocera) from 1976 to 2015: barn owl (Tyto alba (Scopoli); Aves: Tytonidae) (n = 2), snowy owl (Bubo scandiacus (Linnaeus); Aves: Strigidae) (n = 77), great horned owl (Bubo virginianus (Gmelin); Aves: Strigidae) (n = 262), great grey owl (Strix nebulosa Förster; Aves: Strigidae) (n = 142), barred owl (Strix varia Barton; Aves: Strigidae) (n = 10), northern hawk owl (Surnia ulula (Linnaeus); Aves: Strigidae) (n = 18), short-eared owl (Asio flammeus (Pontoppidan); Aves: Strigidae) (n = 74), long-eared owl (Asio otus (Linnaeus); Aves: Strigidae) (n = 67), eastern screech owl (Megascops aslo (Linnaeus); Aves: Strigidae) (n = 59), boreal owl (Aegolius funereus (Linnaeus); Aves: Strigidae) (n = 47), and northern saw-whet owl (Aegolius acadicus (Gmelin); Aves: Strigidae) (n = 44), a total of 802 owls. No lice were found infesting barn owl (Tyto alba (Scopoli); Aves: Tytonidae) or eastern screech owl (Megascops asio (Linnaeus); Aves: Strigidae). We collected a total of 113 810 lice of 12 species: Kurodaia Uchida (Phthiraptera: Menoponidae) – three species; and Strigiphilus Mjöberg (Phthiraptera: Philopteridae) – nine species. Overall prevalence of infestation ranged from 10.0% to 88.9%. Mean intensity for total lice ranged from 22.4 to 506.5. Infestation parameters for each louse–host combination are provided; prevalence and mean intensity were not related for louse–host species combinations. Distribution of louse infestations was highly aggregated. In all louse–host combinations but one, either females were more prevalent than males or there was no significant deviation from 50:50. Male Strigiphilus ceblebrachys Denny significantly outnumbered females in snowy owls. There was a tendency for louse species to co-occur on the same host specimen. Where sample sizes for owls were large enough, no seasonal patterns in abundance of lice were detected.