Geographical localization of the 16 house sparrow populations sampled in this study.

<p>I - Paris (Jardin des Plantes), II - Cachan, III - Wissous, IV - Cosne-Cours sur Loire, V - Rully, 6 - Paris (Cité internationale universitaire), 7 - Gennevilliers, 8 - Le Mans, 9 - Crégy les Meaux, 10 - Berck, 11 - Thieux, 12 - Seninghem, 13 - Ceffonds, 14 - Crennes, 15 - Réaup-Lisse and 16 - Arles. The five populations in roman numbers were sampled for parasite prevalence and intensity. The zoomed region, in the upper right corner, corresponds to the region Ile de France. Scale bar, 100 km for France and 30 km for the region Ile de France.</p

Pearson’s correlation coefficient matrix among the environmental variables used to characterize 16 house sparrow populations in France. * and ** indicates P values ≤0.05 and ≤0.01, respectively.

<p>Pearson’s correlation coefficient matrix among the environmental variables used to characterize 16 house sparrow populations in France. * and ** indicates P values ≤0.05 and ≤0.01, respectively.</p

(a) Negative correlation between Pb concentration in feathers and the axis 1 of the principal component analysis on environmental variables (see materials and methods for more details).

<p>(b) Positive correlation between Cd concentration in feathers and the axis 3 of the principal component analysis. Each point represents a house sparrow population.</p