Blood parasites, body condition, and wing length in two subspecies of yellow wagtail (Motacilla flava) during migration

Abstract

Blood parasites of migrating yellow wagtails of two subspecies--Motacilla flava feldegg and Motacilla flava flava-were studied on a sample of 473 birds caught in spring and autumn periods in Bulgaria. We controlled eight "migration waves" (flocks captured in different evenings) of yellow wagtails for four parameters--average body mass, average fat level, average wing length, and average prevalence of different hematozoan species. Gametocytes or meronts of a total of six species of hematozoa belonging to three genera were identified-Haemoproteus motacillae, Haemoproteus anthi, Plasmodium relictum, Plasmodium subpraecox, Plasmodium cathemerium, and Tryponosoma avium. Mixed infections were detected in 31 cases, of which 14 were of H. anthi/H. motacillae type. Parasite species composition was similar in the two studied subspecies of M. flava. We did not find any significant differences in the overall infection prevalence or number of infecting parasites between M. f. flava and M. f. feldegg. Parasite prevalence and the number of co-infecting parasites in spring were much higher than in fall. Season had a strong influence on the prevalence of H. anthi and H. motacillae, and for both, there was a marginally significant interaction between subspecies and season, but not a season-independent influence of subspecies. Males of M. f. feldegg had a significantly higher overall blood parasite prevalence and prevalence of H. anthi than females. Sex-related differences in the prevalence of other parasites were not significant. Migration waves of yellow wagtails differed in overall infection status and in H. motacillae prevalence, but not for H. anthi prevalence. We also found significant differences in fat score, weight, and wing length between the studied migration waves of the yellow wagtails. Fat scores of birds infected with different hematozoa were lower compared with those of the non-infected birds. This only marginally was true for body weight and was not the case for wing length. Overall, infected birds were in worse condition (estimated as the residual weight after regression with wing length) compared with the non-infected birds, but after controlling for seasonal effects, the differences in condition appeared to be due to migration season and did not significantly differ between infected and non-infected birds caught in the same season.

Biomarkers of animal health: integrating nutritional ecology, endocrine ecophysiology, ecoimmunology, and geospatial ecology

“…Plasma CORT sampled during migration reflects short-term modulation of hormone levels and suppressed responses to environmental stressors to facilitate resource mobilization necessary to fuel costly migration, independent of short-term changes in energetic conditions (Schwabl et al 1991;Holberton et al 1996;Romero et al 1997). We found no relationships between plasma and feather CORT, or parasite loads, which is perhaps a bit surprising, because parasites have been found to impose physiological stress and/ or increase energetic demands (Deviche et al 2001;Mougeot et al 2010;Shurulinkov et al 2012). However, like most trade-offs the effects of parasites on other life processes may only be apparent under compounding environmental stressors, like food shortages or poor health that create more variance in a population (Merino et al 2000;Tomas et al 2007;Mougeot et al 2010).…”

“…; Shurulinkov et al. ). However, like most trade‐offs the effects of parasites on other life processes may only be apparent under compounding environmental stressors, like food shortages or poor health that create more variance in a population (Merino et al.…”

“…; Shurulinkov et al. ). Thus for these fall‐migrating saw‐whet owls, parasites did not appear to impose a detectable increase in CORT levels and thus may not represent a large energetic burden.…”

Body Mass, Wing Length, and Condition of Wintering Ducks Relative to Hematozoa Infection

“…However, in some cases, relationships between hematozoa infection and measures of body mass, body condition, and survival varied among hematozoa genera infecting birds and demographic characteristics of host populations including species, age, and sex (Schrader et al 2003;Ishak et al 2010;Lachish et al 2011;Rojo et al 2013;Meixell et al 2016). Other studies have found no relationship between hematozoa infection and bird growth (Shutler et al 1999b), wing length (Shurulinkov et al 2012), body mass (Bennett et al 1988;Shurulinkov et al 2012;Shutler et al 1999b), condition (Ashford 1971;Shurulinkov et al 2012;Sorensen et al 2016), or other health metrics (Shutler et al 1996(Shutler et al , 1999bStjerman et al 2004). Thus, targeted investigations are necessary to assess the effects of hematozoa infection on specific avian populations of interest.…”

The evidence for rapid gametocyte viability changes in the course of parasitemia in Haemoproteus parasites

“…Blood parasites of the genus Haemoproteus (Haemosporida, Haemoproteidae) are widespread in birds (Bensch et al 2009), and some of their species have been reported to affect bird fitness and even cause severe diseases both in avian hosts and blood-sucking insects (Marzal et al 2005;Ferrell et al 2007;Pacheco et al 2011;Shurulinkov et al 2012;Perkins 2014;Valkiūnas et al 2014a;Valkiūnas 2015). Sexual process and sporogony of avian haemoproteids occur in species of the Ceratopogonidae and Hippoboscidae, which transmit these pathogens (Atkinson et al 2008).…”