Francisco Gutiérrez-Corchero

Biometric differences among the Dipper Cinclus cinclus populations 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 Bergmanns 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.

Biometrics of the Southern Grey Shrike Lanius meridionalis in relation to age and sex

The biometrics of Southern Grey Shrike Lanius meridionalis and differences from the closely related Great Grey Shrike L. excubitor are poorly characterised. The aim of this study was to describe sex and age variation in external biometric measurements for the nominate Southern Grey Shrike L. m. meridionalis in a population from northern Spain. In total, 174 Southern Grey Shrikes were ringed, measured, and sexed by molecular techniques. The overall biometry of the shrikes was summarised by Principal Components Analysis (PCA). There were significant differences in size between sex and age classes. We observed a sexual dimorphism in size, with adult males the largest and yearling females the smallest. According to the PCA, only the first principal component showed significant sex and age differences, and these were related to the tail, wing, third primary, white on primaries and white on rectrices. According to these data, and at least in terms of biometry, the Southern Grey Shrike is more similar to the Loggerhead Shrike L. ludovicianus than to the Great Grey Shrike.

Breeding Success of Southern Grey Shrikes Lanius meridionalis in Agricultural Areas: The Influence of Nest Site Characteristics

Abstract. Three hundred and thirty nests of Southern Grey Shrike Lanius meridionalis were located during 1998–2010 in two highly fragmented Mediterranean agricultural areas of Spain (Olite in Northern and Toro in Western part of the country). Most nests (ca. 85%) were built in thorny shrubs (mainly Dog Rose Rosa sp. and Blackberry Rubus ulmifolius) and thornless shrubs (mainly Holm Oak Quercus rotundifolia and Kermes Oak Quercus coccifera). Based on a logistic regression, three factors had an influence on breeding success: study area, breeding phenology, and plant cover type. Location of the nest inside the shrub, as well as luminosity inside a shrub varied between studied shrub species, but did not significantly affect breeding success. The percentage of successful nests was significantly higher in Olite than in Toro (64.5% and 37.9% respectively). In Olite, but not in Toro, clutches laid early (first egg laid prior to 1st May) were more successful than clutches laid late. The highest breeding success was recorded in nests located in thorny shrubs and, especially, in those found in Blackberry bushes. Conservation of Blackberry shrubs appears to be an appropriate measure to increase breeding success of the Southern Grey Shrike.

Seasonal Variation in the Body Size-Body Mass Relationship in the Southern Grey Shrike Lanius meridionalis

Abstract. The variation of male (n = 105) and female (n = 107) Southern Grey Shrike body mass has been analyzed in northern Spain during 2000–2002. The annual cycle was divided into autumn (October and November), winter (December to February) and breeding season (March to July), the latter subdivided into egg incubation, small nestlings and large nestlings periods. In order to analyze body mass, the residual index (RI) was used because it corrects body mass related to body size. The mean RI value for males was negative during the whole breeding season and positive during autumn and winter and it did not vary greatly between the periods. In females, the mean RI was definitely greater during egg incubation compared to other periods. The RI value of females was higher than that of males during the egg incubation and large nestlings periods, showing no significant differences in other periods. Female Southern Grey Shrikes (but not males) fitted to the programmed anorexia hypothesis during the breeding season whereas in winter they did not increase their body mass, in clear contrast to what has been put forward in some theoretical models.

Haemosporidian prevalence in Southern Grey Shrike Lanius meridionalis nestlings: impact on body condition and geographic distribution in the Iberian Peninsula

ABSTRACT Capsule: Nestling Southern Grey Shrikes Lanius meridionalis show a high prevalence of haemosporidian parasites including five lineages described here for the first time. Aims: To examine the prevalence of various haemosporidian lineages in nestlings of three separated Iberian populations of the Southern Grey Shrike. Methods: Blood samples were taken from nestling Southern Grey Shrikes from three agroecosystem areas in the Iberian Peninsula. Parasites were detected from blood samples using polymerase chain reaction screening. Resusts: Nestlings were parasitized by 11 different lineages belonging to the genera Haemoproteus (3.8%), Plasmodium (0.5%) and Leucocytozoon (1.8%), including five new undescribed lineages. These are among the highest prevalence levels of haemosporidians parasites (7.4%) for nestlings of passerine birds. Conclusion: Our findings suggest that the distribution of avian haemosporidians is determined by complex effects including climate and biogeography. Most parasite lineages were not universally spread across shrike populations, despite being otherwise widespread both geographically and taxonomically.