Interspecific Variability of Prevalence in Blood Parasites of Adult Passerine Birds During the Breeding Season in Alaska

Abstract

Blood parasite prevalence based on microscopic examination of stained blood smears was determined in adults of 11 passerine bird species sampled during their breeding season (May and June 1997-98) in interior Alaska (USA). These species included primarily Nearctic migratory species such as the dark-eyed junco (Junco hyemalis) and neotropical migratory species such as the blackpoll warbler (Dendroica striata), alder flycatcher (Empidonax alnorum), Swainson's thrush (Catharus ustulatus), northern waterthrush (Seiurus noveboracensis), and bank swallow (Riparia riparia) as well as one long-distance palearctic migrant, the arctic warbler (Phylloscopus borealis). The more prevalent parasites were Leucocytozoon dubreuili (73% of the sampled turdinids), L. fringillinarum (42% of the sampled fringillids and parulids), and Trypanosoma avium (39% of the sampled hosts). Other parasites (H. fallisi: 18% of the sampled turdinids; Haemoproteus paruli: 14% of the sampled parulids; H. fringillae: 5% of the sampled fringillids; microfilariae: 4% of the sampled hosts) were observed less frequently. Plasmodium vaughani was found only in two yellow warblers (Dendroica petechia). Overall parasite prevalence varied between 0% in the alder flycatcher to Ͼ80% in Swainson's thrush, arctic warbler, and Townsend's warbler (Dendroica townsendi). Prevalence of various hematozoa also was bird species-dependent. No relationship was observed between prevalence and either foraging (aerial versus trees/shrubs) or nesting habits (ground versus arboreal) or general location of the wintering area of the different species examined. Prevalence also was unrelated to average dates of arrival on breeding grounds and, therefore, to potential duration of exposure to local insect vectors before capture. Differences in blood parasite prevalence among species breeding in a same region and in the same type of habitat may result from differences in host specificity such as immunological resistance to infection or blood meal preference by potential vectors and/or in behavioral adjustments/physiological traits that alter exposure to vectors.

Trypanosoma aviumincidence, pathogenicity and response to melarsomine in falcons from Kuwait

“…This might explain the observation of clinical signs in infected birds, since it seems reasonable to assume that the higher the number of parasites the more pathogenic is their action. The 1.3 % incidence reported here is low if compared with studies from areas at higher latitudes (Rintamaki et al, 1999 ;Deviche et al, 2001 ;Holstad et al, 2003), taking also into account that the population examined includes 921 'diseased' falcons and not one healthy falcon. However, results from studies carried out on freeranging falcons admitted to wildlife rescue centres, accordingly to be considered 'diseased', are overlapping.…”

“…This assumption does not seem to be based on verifiable facts but on the lack of direct research, since today only morphological (Yurchenko et al, 1999) and epidemiological informations (Kirkpatrick & Lauer, 1985 ;Munoz et al, 1999) are available. Most of previous studies were carried out on wild animals captured and released after sampling (Rintamaki et al, 1999;Deviche et al, 2001;Holstad et al, 2003 pathogenic effects are easier to detect and to describe. This seems to be the first attempt to study clinical signs and the response to therapy of T. avium infection in captive birds of prey.…”

Prevalence of Hematozoa Infections Among Breeding and Wintering Rusty Blackbirds

“…Both intra-and interspecific variation in the prevalence of blood parasites is well documented (Merilä et al 1995), and factors contributing to this variation are quite varied (Deviche et al 2001). It was not clear why the prevalence of hematozoan infections among Rusty Blackbirds in Alaska (44%) is less than half that reported from Newfoundland (100%; ) and intermediate in Maine (67%).…”

Effect of Haemoproteus columbae infection on the hemogram of the Pigeons (Columba livia domestica)

“…ranged from 20 to 32 %. The prevalence of blood parasite in pigeons and birds in Japan (Murata 2002), Costa Rica (Valkiunas et al 2004) and Alaska (Deviche et al 2001) was shown to be lower than 10 %. H. columbae infects pigeons which are associated with human settlements.…”