712 Seasonal population dynamics of four species of chewing lice (Phthiraptera: Menoponidae, Philopteridae) on feral pigeons (Aves: Columbiformes: Columbidae) Terry D. Galloway,1 Robert J. Lamb Abstract—Seasonal dynamics of louse (Phthiraptera) populations on feral pigeons, Columba livia Gmelin (Aves: Columbiformes: Columbidae) were investigated from 2003 to 2012 in southern Manitoba, Canada. Pigeons were infested with: Philopteridae – Campanulotes compar (Burmeister), Columbicola columbae (Linnaeus), and Coloceras tovornikae Tendeiro; Menoponidae – Hohorstiella lata (Piaget). We consider the hypothesis that four species living on the same host show similar seasonal dynamics, coordinated by the life history of the host. Adults of both sexes and nymphs of all four species were present on pigeons throughout the year, consistent with continuous feeding and reproduction. Campanulotes compar and C. columbae populations were low in spring and peaked in September, with C. columbae showing greater seasonal changes for all population parameters. Coloceras tovornikae showed two annual peaks in abundance in spring and late summer, and H. lata was most abundant in the cold months of the year. Over 10 years, the four species showed distinct seasonal dynamics, although they live on the same birds. Seasonal patterns provided no evidence that louse reproduction or abundance is coordinated by the long breeding and moulting seasons of the host. Introduction (Galloway and Lamb 2014). Campanulotes compar and C. columbae are abundant and their populations Four species of chewing lice (Phthiraptera) are relatively stable from year to year, whereas infest feral pigeons, Columba livia Gmelin (Aves: C. tovornikae and H. lata are less abundant and less Columbiformes: Columbidae) in Manitoba, stable than the former species. Canada: Philopteridae – Campanulotes compar The habitat of bird lice, the surface of the body (Burmeister), Columbicola columbae (Linnaeus), of the host, has a relatively constant temperature and Coloceras tovornikae Tendeiro; Menoponidae – through the season, in comparison with the Hohorstiella lata (Piaget) (Galloway and Palma changes in ambient air temperature experienced 2008; Galloway and Lamb 2014). These species by the host, particularly in a continental climate occupy the skin or feathers of their host (Nelson and such as that of Manitoba. Seasonal changes in Murray 1971; Singh et al. 2000), often on the same louse populations might be expected to be more bird, and all have chewing mouthparts: three are muted than those of multivoltine insects more feather feeders (Philopteridae) and one feeds on openly exposed to ambient temperatures (Woodman blood (Menoponidae) (Galloway and Palma 2008). and Dicke 1954). On the other hand, many bird Coloceras tovornikae appears to be a relatively recent species exhibit seasonal changes in their life introduction into North America (Galloway and histories associated with migration, moulting, and Palma 2008), compared with the other three species, reproduction, which may affect the seasonal which may have been introduced to North America biology of their ectoparasites. Foster (1969) along with the rock pigeon. Nevertheless, each concluded that the life cycles of a warbler and its species has a characteristic population biology blood-feeding chewing lice (Ricinus picturatus Received 19 May 2014. Accepted 24 September 2014. First published online 20 January 2015. T.D. Galloway,1 R.J. Lamb, Department of Entomology, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2 1Corresponding author (e-mail: [email protected]). Subject editor: Heather Proctor doi:10.4039/tce.2014.84 Can. Entomol. 147: 712–722 (2015) © 2015 Entomological Society of Canada Galloway and Lamb 713 (Carriker) and Menacanthus Neumann species) Prairie Wildlife Rehabilitation Centre (Winnipeg, were synchronised: oviposition by lice coincided Manitoba, Canada). All came from southern with the short nesting period of its host. She Manitoba, Canada, mostly from Winnipeg. The found no evidence that oviposition occurred when majority of birds were euthanised soon after birds moulted. Hamstra and Badyaev (2009) arrival, immediately placed in sealed plastic bags, hypothesised that ectoparasite populations thrive and frozen for at least 48 hours until they could be at particular points in the life history of their avian processed. Lice were collected by washing hosts, because the energetic requirements of pigeons (Mironov and Galloway 2002), and this moulting or breeding limit immune responses and method removes nearly all lice from the host preening behaviour, the main defences against (Clayton and Drown 2001; T.D.G., personal ectoparasites. Little information is available on observation). The samples of pigeons and lice are the seasonal dynamics of lice on birds to assess described in detail by Galloway and Lamb (2014). these hypotheses. To date, studies of seasonal For the years 2003–2012 the following data dynamics are based on examination of museum were considered for each species of louse and specimens for the presence of eggs (Foster 1969) each pigeon: collection date, number of lice, or collections from birds through one year (e.g., number of adult females and males, and number Boyd 1951; Woodman and Dicke 1954; Kettle of nymphs. Nymphs were not sexed. Eggs were 1983; Spitznagel 1985; Chandra et al. 1988; not removed reliably by washing and so were not Petryszak et al. 2000; Hamstra and Badyaev tallied. The 10 chicks in the sample were excluded 2009), or over a relatively short period of time, from parameter estimates because they came up to three years (Boyd 1951; Bergstrand and from a restricted part of the season, whereas Klimstra 1964; Tuleshkov 1965; Baum 1968; the 49 juveniles and larger sample of adults Eveleigh and Threlfall 1976). were distributed throughout the year. Data for Feral pigeons in Winnipeg, Manitoba are 11 pigeons were excluded because they were abundant and non-migratory, with high winter considered outliers with extremely high infesta- counts compared to many other locations in North tions of one louse species (>10 times mean American (Taylor 2003). Pigeons alternate intensity) (Galloway and Lamb 2014). If they had between phases of roosting communally and a been included, the high louse numbers would long breeding season. In Manitoba, pigeon eggs have biased estimates of peak seasonal abun- have been observed in nests between 16 April and dance, assuring that the month of peak seasonal 29 July, and at least two broods may be produced abundance was determined by the collection date each year (Taylor 2003). In one previous study of of a single, heavily infested bird. The excluded seasonality of louse populations on pigeons in birds comprised 2% of the total, leaving 542 birds. Poland, Petryszak et al. (2000) found the greatest The number of pigeons available in each year abundance of C. compar in July and C. columbae ranged from 26 to 126, and in seven of the years in autumn. 41 or more birds were assessed each year. We investigate the seasonal population Data for the 10 years were first partitioned into dynamics of four species of lice on feral pigeons samples for each month, providing a mean of to assess whether differences in seasonality 45 ± 9 (SD) pigeons per month. Abundance, contribute to the species-specificity of population prevalence, intensity, ratio of males to females, processes of these lice and whether louse season- and ratio of nymphs to females were estimated for ality is coordinated by pigeon life history. each month and louse species. Prevalence is the proportion of birds infested by a louse species, intensity is the number of lice of that species on an Materials and methods infested pigeon, and louse abundance equals prevalence multiplied by intensity (Rózsa et al. Ten years of data are used to describe seasonal 2000). This monthly partition provided an overall patterns in the abundance of lice on pigeons picture of the dynamics of each louse species over salvaged from rehabilitation hospitals at the the year, but no indication of how uniform any Wildlife Haven (Manitoba Wildlife Rehabilitation seasonal patterns were from year to year. In some Organization, Winnipeg, Manitoba, Canada) and years, the number of pigeons available some © 2015 Entomological Society of Canada 714 Can. Entomol. Vol. 147, 2015 months was inadequate to effectively compare the same month or season ranked lowest or monthly estimates among years, in part because of highest was determined. If the same month or the large difference in louse abundance among season always, or nearly always, ranked lowest pigeons. Many pigeons had no lice, particularly or highest, this result provided evidence for the less common louse species, assuring that seasonal patterns in parameter values. abundance was not normally distributed (Galloway The degree of seasonality, or degree to which a and Lamb 2014). parameter value changed over the year, was To help assess year-to-year variation in season- quantified for each louse species in two ways. ality, data also were partitioned into four seasons: First, the coefficient of variation (CV) and its 95% winter (December, January, and February), spring confidence interval (corrected following Sokal (March, April, and May), summer (June, July, and and Rohlf (1981)) was calculated for the August), and autumn (September, October, and 12 monthly estimates. The confidence intervals November). For each of seven years of the study allowed apparent differences among louse species (2004,