Factors that determine the presence of avian malaria in House Sparrows in the east of the Iberian Peninsula

Abstract

The House Sparrow (Passer domesticus) is one of the most common birds in human-altered environments worldwide. Despite this, a significant population decline has been recorded in most regions where this species is native since the last decades of the previous century. The Valencian Community, in eastern Spain, is one of the areas where this decline was first reported in the country. The causes of this decline remain unclear and have been attributed to several factors, including agricultural intensification, land use changes, predation, pollution, and disease. Avian malaria, caused by parasites of the genus Plasmodium, is considered one of the possible contributing factors, particularly in urban and suburban areas. It has also been shown that population growth rate is inversely proportional to infection intensity. The aim of the present study was to assess the prevalence of haemoparasitic infections in several House Sparrow populations across different localities in eastern Spain (Valencian Community). Furthermore, we used Generalized Linear Mixed Models (GLMMs) to explore which biological and/or environmental factors best explained the prevalence of infection, including age, sex, Scaled Mass Index (SMI), and habitat type (urban vs. rural). The overall prevalence of haemoparasitic infection was 11.9%, and no significant explanatory variables were identified in the GLMM. Malaria prevalence was similar to that reported in other regions of Spain but considerably lower than the prevalence recorded in other European countries.