Variation in infection status among bird populations, and its implications for the successful co-introduction of parasites in bird translocations

Many United Kingdom (UK) bird species were introduced to New Zealand in the mid-to-late 1800’s. These species host chewing-lice parasites (Insecta; Phthiraptera). Some of these parasite species failed to establish in New Zealand (NZ) while their host species succeeded. Several explanations have been offered for this phenomenon: (1) parasite taxa never left the United Kingdom (missed the boat); (2) host taxa left the UK but did not establish in NZ (sank with the boat); (3) parasite taxa that did not survive on introduced host taxa that established in NZ (lost overboard). To determine whether host source location is an explanation for why some parasite species miss the boat, this masters research focuses on UK geographic distributions of host (passerine) and parasite (chewing-louse) species. New UK louse data were collected from an area where previous sampling is sparse, and combined with other recent and historic parasite records. Louse intensity, prevalence and range are reported for lice collected as part of this study. A Bayesian multilevel logistic regression model was used to analyse whether the probability of the number of parasitised hosts differed between six geographic regions, two sampling methods, three sampling periods and louse phylogeny. Hosts in northern UK regions were less likely to be infested than in other regions. Hosts were less likely to be infested with ischnoceran lice than amblyceran lice. This study highlights the need to account for variations in louse prevalence at host source locations when modelling the probability of presence on a given host population. To obtain more precise prevalence and intensity parameters, future researchers should focus on sampling a greater number of hosts