Biometric Differences Among the DipperCinclus cinclusPopulations of Spain

Abstract

The length of the tarsus and wing, and the weight of the Dipper were measured in four mountain ranges in Spain (Cantabrian Mountains, western Pyrenees, the Central Mountains and Sierra Nevada). Birds from the Sierra Nevada were the largest but there were no significant differences among the other three areas. In the north, the range of the C. c. cinclus and C. c. aquaticus subspecies overlapped. In the south only aquaticus was present and in the central mountains only cinclus. The biometrics of cinclus in the north and centre were similar but aquaticus was larger in the south than the north. Spanish populations of C. cinclus thus appear to go against the predictions of Bergmann's rule. The residual index (RI) was calculated for individual birds from the regression of mass/tarsus length. RI was higher in males than females in the northern populations, but the same in the centre and south. According to this index, males (but not females) were heavier than the theoretical weight in the north and lighter in the centre and southern ranges. Some other variations in the Spanish populations are also discussed.