Parasite Pressure and its Effects on Blood Parameters in a Stable and Dense Population of the Endangered Lesser Grey Shrike

Abstract

The risk that pathogens and parasites pose to endangered species is increasingly evident. Nonetheless, this is frequently overlooked when considering causes of decline of species and conservation practices. Here, we study the ecto and haemoparasites of adult and nestling Lesser grey shrikes Lanius minor from a dense and stable breeding population in central Europe and their effect on host blood parameters. We found three species of haemoparasites (Haemoproteus sp., microfilariae tentatively assigned to the family Splendidofilariae and Trypanosoma sp.) and two ectoparasite taxa (Menacanthus camelinus and feather mites -Acarina-). Our data suggest that the studied population, located in an area with traditional and extensive farming, is not under a strong parasite pressure. Despite this, indirect measures of immunocompetence (haematocrit and sedimentation rate) showed an association between haemoparasites and health status: while haematocrit did not differ between parasitised and non-parasitised individuals, adult shrikes with haematozoa had significantly lower sedimentation rates than did non-parasitised birds.

Effects of malaria double infection in birds: one plus one is not two

“…, 2005), whereas others have reported no change (Shutler et al. , 1996; Ots & Hõrak, 1998; Valera et al. , 2005) or even increased levels (Dawson & Bortolotti, 1997; Johnsen & Zuk, 1998; Merino et al.…”

Patterns in the distribution of avian lice (Phthiraptera: Amblycera, Ischnocera) living on the great grey shrike Lanius excubitor

“…Although the effect of parasites on other disease agents on shrikes has been scarcely documented (Lefranc and Worfolk 1997; but see Valera et al 2006), the available information are mainly records of parasite occurrence and taxonomic works (Hromada et al 2000;Skoracki et al 2001Skoracki et al , 2002Votypka et al 2003). We suggested that future studies on feather lice fauna should be done on wild, living birds and to link lice abundance with the shrikes' health status (for one exceptional example, see Valera at al.…”

“…To date however, knowledge of common parasites infecting birds is sometimes limited. This inhibits more detailed analysis and, hence, more data are still necessary (Lindell et al 2002;Valera et al 2006).…”

“…Therefore, because the species shows a decline in population size and geographical range (Lefranc and Worfolk 1997;Antczak et al 2004), the study may have conservation implications (cf. Valera et al 2006).…”

Unravelling causality from correlations: revealing the impacts of endemic ectoparasites on a protected species (tuatara)

“…Few studies of threatened species can explore the effects of endemic parasites through experimental manipulation, thus most are limited to observational datasets to infer the costs of parasites to hosts (Valera et al 2006 ;Bunbury et al 2007Bunbury et al , 2008Zhang et al 2008). Since threatened species are often subjected to numerous sources of stress (Lafferty and Kuris, 1999), negative correlations between infection and body condition could have other causes.…”