Blood Constituents and Their Relation to Diet in Urban and Rural House Sparrows

To determine whether habitat-related differences in diets of House Sparrows (Passer domesticus) were reflected in their blood, we measured hematocrits and plasma concentrations of cholesterol, albumin, uric acid, and blood urea nitrogen (BUN) of sparrows from urban and rural habitats in Centre County, Pennsylvania, during the breeding season. We also determined the protein and fat content of food samples recovered from sacrificed birds. Significantly elevated plasma cholesterol and BUN levels in House Sparrows from the urban area reflected the higher fat and protein content of the urban diet. Albumin and uric acid levels were also higher in urban than in rural birds, but not significantly so. Blood values were further influenced by age, sex, and date of collection. The analysis of blood may be useful in assessing the quality of diets eaten by wild birds.