Body condition and colonization by fungi of House Sparrows Passer domesticus in the urban and rural environment

Abstract

Mycoses of wild birds are rarely addressed in scientific research. We tested the hypothesis that urban populations of House Sparrow Passer domesticus, which in many cities showed downward trends in their number and are characterized by lower body mass and poorer body condition, would be more frequently colonized by fungi. To evaluate the degree of bird colonization by fungi, swabs were taken from the beak cavity and cloaca of birds from urban and rural populations in the breeding season. A high degree of bird colonization by fungi was determined in both types of habitats (urban: 86% of population; rural: 92% of population). In total, 26 species of fungi were isolated (urban: 15 species; rural: 22 species). No significant differences were determined between the number of fungi species identified in birds from urban and rural habitats and between the degree of colonization of the two ontocenoses (beak cavity and cloaca). In both environments, Candida krusei turned out to be the prevalent fungus, with a clear predominance in the urban population. The extent of ontocenoses colonization was higher in adult than in juvenile birds, which indicated that the colonization of ontocenoses progresses with age. A significant correlation was found between the presence of fungi, lower values body condition parameters from the urban population (F – degree of fat score, logBM – body mass logarithm, logT – tarsus length logarithm, BM/WL –body mass/wing length, logBM/logWL, BM/TL – body mass/tail length), physiological condition, and age of birds, which may suggest that adults birds with worse condition, and higher haemoglobin level were more often colonized by fungi. No important differences in the fungal colonization were detected between urban and rural areas, thus, the hypothesis that fungal infection may be the cause of decline of sparrows in urban habitats is still to be demonstrated.