Biology session

The Dunnock (Prunella modularis) is a sporadic breeder and wintering species but a common passage migrant in the Carpathian Basin. Despite the large number of birds passing through the region, little is known on migration. The Dunnock has 8 subspecies, distributed in the temperate zone of Eurasia. The birds found in the Carpathian Basin belong to the nominotypical subspecies: Prunella modularis modularis. The P. m. modularis is a partial migrant and its migratory route extends towards the South-West direction. Probably, the birds breeding in Fenno-Scandinavia migrate through the Carpathian Basin. Their wintering area is located mainly on the Apennine Peninsula. Their spring and autumn migration lasts from March to April, and from the end of September to the beginning of November, respectively.

The trapping and ringing work were carried out in the Danube-Ipoly National Park, at the Ócsa Bird Ringing Station using the standard methods of Actio Hungarica. I analysed the data of the birds captured between 1984 and 2015. I took the age of the birds (adults and juveniles) into account in the analyis of autumn data. However the distinction of the birds’ sex is not possible in any migration period.

I used linear mixed models to analyse the migration timing and the biometric variables in spring and in autumn separately and their changes during the 32 years. I also analysed the pattern of recaptures.

According to my results, the timing of migration did not change significantly in any of the seasons during the study period. Based on the within-year recaptures, the spring migration is quicker than the autumn migration. The average wing length and the length of the third flight feather increased significantly during spring. The cause of this might be that the usually longer winged males migrate earlier. The average body mass increased significantly during autumn. The cause of this might be that these birds arrive from averagely shorter distance. Another possible reason can be the physiological acclimatization related to colder days.

I did not find significant biometrical difference between the seasons, hence I hypothetize that the same population migrates through the area in the two seasons.

All of the measured variables – except body mass – of the juvenile birds were lower on average than that of the adults’. I did not find any change in the migrational dynamics, nor in the biometrical variables, that could be a response to climate change, detected in case of several species.