Avian Hemosporidian Parasites from Northern California Oak Woodland and Chaparral Habitats
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Journal of Wildlife Diseases, 44(2), 2008, pp. 260–268 # Wildlife Disease Association 2008 AVIAN HEMOSPORIDIAN PARASITES FROM NORTHERN CALIFORNIA OAK WOODLAND AND CHAPARRAL HABITATS Ellen S. Martinsen,1,4 Benjamin J. Blumberg,1 Rebecca J. Eisen,2,3 and Jos J. Schall1 1 Department of Biology, University of Vermont, Burlington, Vermont 05405, USA 2 Division of Insect Biology, 201 Wellman Hall, University of California, Berkeley, California 94720, USA 3 Current Address: Division of Vector-Borne Infectious Diseases, Centers for Disease Control and Prevention, PO Box 2087, Fort Collins, Colorado 80522, USA 4 Corresponding author (email: [email protected]) ABSTRACT: During spring–summer 2003–2004, the avian community was surveyed for hemosporidian parasites in an oak (Quercus spp.) and madrone (Arbutus spp.) woodland bordering grassland and chaparral habitats at a site in northern California, a geographic location and in habitat types not previously sampled for these parasites. Of 324 birds from 46 species (21 families) sampled (including four species not previously examined for hemosporidians), 126 (39%) were infected with parasites identified as species of one or more of the genera Plasmodium (3% of birds sampled), Haemoproteus (30%), and Leucocytozoon (11%). Species of parasite were identified by morphology in stained blood smears and were consistent with one species of Plasmodium, 11 species of Haemoproteus, and four species of Leucocytozoon. We document the presence of one of the parasite genera in seven new host species and discovered 12 new parasite species–host species associations. Hatching-year birds were found infected with parasites of all three genera. Prevalence of parasites for each genus differed significantly for the entire sample, and prevalence of parasites for the most common genus, Haemoproteus, differed significantly among bird families. Among families with substantial sample sizes, the Vireonidae (63%) and Emberizidae (70%) were most often infected with Haemoproteus spp. No evidence for parasite between-genus interaction, either positive or negative, was found. Overall prevalence of hemosporidians at the northern California sites and predominance of Haemoproteus spp. was similar to that reported in most other surveys for the USA, Canada, and the Caribbean islands. Key words: Avian malaria, California, Haemoproteus, Hemosporidia, Leucocytozoon, Plasmodium. INTRODUCTION poboscid flies (Hippoboscidae), Plasmodi- um spp. by mosquitoes (Culicidae), and The avian hemosporidian parasites Leucocytozoon spp. by blackflies (Simuli- (phylum Apicomplexa) are taxonomically idae) (Valkiunas, 2005). diverse, cosmopolitan in distribution, and Surveys of local bird assemblages com- have been reported infecting hosts from pleted in many regions of the world most bird families (Valkiunas, 2005). More suggest that the prevalence of parasites than 200 described species are classified placed into Plasmodium, Haemoproteus, into three genera, Plasmodium, Haemo- and Leucocytozoon differs geographically. proteus,andLeucocytozoon.Levine For example, Leucocytozoon spp. appear (1988) places the three genera into a common in birds of temperate regions, single family, the Plasmodiidae, whereas even including high latitudes in the Valkiunas (2005) separates Leucocytozoon subarctic, but are rare or absent from into its own family, the Leucocytozoidae. neotropic locations (Greiner et al., 1975; The broad landscape ecology and trans- White et al., 1978; Valkiunas, 1996, 2005). mission dynamics of parasites of the three Such patterns may be driven by habitat genera are likely to differ because para- quality affecting host and vector density sites placed into different genera exploit and the systematic composition of the bird different taxa of blood-feeding vectors communities. The latter possibility is with different habitats and biting behavior. particularly intriguing because the preva- Haemoproteus spp. are transmitted by lence of hemosporidians appears to vary biting midges (Ceratopogonidae) and hip- among bird families perhaps because of 260 MARTINSEN ET AL.—CALIFORNIA AVIAN HEMOSPORIDIA 261 differential susceptibility and other host- shown to be hosts for hemosporidians; 3) parasite interactions (Greiner et al., 1975). to determine whether hatching-year birds Although parasites in the three genera are infected, an indication of transmission have the same basic life cycle, differences at the study sites; 4) to determine whether in vertebrate host tissues infected and parasites for the three genera differ in intensity of blood stages may lead to prevalence by bird family; 5) to examine different levels of virulence. Plasmodium the data for suggestions of interactions spp. and Leucocytozoon spp. are viewed as between parasites of the three genera; and the more virulent parasites, although 6) to compare the prevalence results with Haemoproteus spp. have also been shown those from other surveys of avian hemos- to be detrimental to their avian hosts poridian parasites. (Atkinson and van Riper, 1991; Valkiunas, 1993; Valkiunas 2006). Thus, variation in METHODS prevalence and virulence of parasites placed in the three genera must play a The study location was the Hopland role in the parasite-host biology of avian Research and Extension Center (HREC), hemosporidians, including their overall a 2,169-ha tract located near the town importance for the ecology of their bird of Hopland in southern Mendocino hosts. County, California, USA (39u009220N, Local surveys for malaria parasites and 123u059130W). The climate at Hopland is other hemosporidians in North American Mediterranean, with hot, dry summers bird communities have been unevenly and cool, wet winters. Annual rainfall distributed both geographically and taxo- averages 937 mm, and July to August nomically, with most studies grouped in maximum temperature averages 33 C the eastern USA and southern Canada, (HREC records from 1953 to 2000). with a focus on perching birds (Passer- Twelve collecting sites were selected over iformes). Only a few surveys have been an elevational gradient from 320 to 810 m. reported for California, USA, birds: the Lower-elevation sites were oak/madrone Sacramento region in the Central Valley woodland bordering open grass habitat, (Herman et al., 1954; Clark and Swine- dominated by Quercus spp. and Pacific hart, 1966), an island and mainland madrone (Arbutus menziesii). Habitats in northern coastal scrub habitat (Super higher sites were oak woodland bordering and van Riper, 1995), and the Los Angeles chaparral. These are typical habitats of region and southward (Wood and Wood, coastal valleys and ridges. Further infor- 1937; Herms et al., 1939). Here, we report mation on these sites is presented in Eisen the first survey from northern California et al. (2004, 2005). Birds were captured by from an oak/madrone woodland bordering mist-nets, without any use of call playback open grass and an oak woodland bordering to prevent luring in birds from other chaparral, habitats characteristic of the habitats. Each captured bird was identi- valleys of the coastal ranges. Our goals in fied to species and age based on criteria in this study were 1) to determine the Pyle (1997), and a blood sample taken by prevalence of hemosporidian parasites, brachial venipuncture. Thin smears were identified to genus and species, in a made on microscope slides, fixed in the complex avian community that has not field with absolute methanol, and later been surveyed before, with an emphasis stainedwithGiemsastain(pH7.0). on the relative prevalence of parasites of Smears were examined first at 1003 for the three genera Plasmodium, Haemopro- 3–5 min (approximately 23106 blood cells teus, and Leucocytozoon; 2) to document examined) for detection of Leucocytozoon the host range of the parasites, including spp. infections with low parasitemia. bird species that have not previously been Leucocytozoon parasites are obvious un- 262 JOURNAL OF WILDLIFE DISEASES, VOL. 44, NO. 2, APRIL 2008 der 1003 magnification, as are most previously been sampled for avian hemos- gametocytes of Haemoproteus spp. and poridians. A total of 126 birds were infected Plasmodium spp. Each slide was then with parasites of one or more of the genera examined under 1,0003 for an additional (39% of birds), 10 with Plasmodium spp., 5–8 min (approximately 33104 blood 96 with Haemoproteus spp., and 36 with cells). Smears from infected birds were Leucocytozoon spp. (Table 1). Overall then examined at 1,0003 for the entirety prevalence of parasites within the three of the slide (upwards of 1 hr) to examine genera differed significantly. Haemoprote- many parasite cells for identification to us spp. were the most common parasites genus and species. All slides are on deposit (30% of all birds examined, 76% of birds at the University of Vermont Thompson with an infection [95% confidence interval Zoology collections. {CI}50.6820.83]), Leucocytozoon spp. Identification of parasites was based on were also common (11% and 29% Valkiunas (2005) and numerous original [CI50.21–0.37]), and Plasmodium spp. species descriptions. We present identifi- rare (3% and 9% [CI50.03–0.14]). Table 1 cations of parasites to genus with confi- presents the bird species in the sample by dence because Leucocytozoon is distinct in family, infection status by genus and morphology from the other genera, and species, and documentation of infection with experience, the difference between by parasites from the three genera reported gametocytes of Plasmodium and Haemo-