Comparability of Wing Length Measurements Based on Data Collected at two Twin Stations during Migration

Zaniewicz G. 2012. Comparability of wing length measurements based on data collected attwo twin stations during migration. Ring 34: 37-43.

Data collected during bird migration include measurements taken during ringing. The variety and quality of information, which these measurements can potentially provide, depend strongly on their accuracy and comparability.

The analysis of the comparability was made based on the measurements of wing length taken by different ringers during autumn migratory seasons at the southern Baltic coast. An experiment was run with the measurements taken from six passerine species during several (from 8 to 10, depending on the species) migratory seasons at two twin sites belonging to Mierzeja Wioelana station. Pearson’s correlation coefficient was used to evaluate how strongly the habits of different measurers influence the measurements taken. The results of this experiment show that correlations between the measurements collected at these two sites are strong and statistically significant for the Blackcap (Sylvia atricapilla), Garden Warbler (Sylvia borin), Robin (Erithacus rubecula) and Song Thrush (Turdus philomelos). However, for the Goldcrest (Regulus regulus) and Willow Warbler (Phylloscopus trochilus) the relations were not significant. The last species allow to consider other causes, independent from human factor, which are possibly responsible for the average wing length local variability. In such species, we still need to look closer at the potential sources of their differentiation, such as the preferences of habitat selection between sexes, populations, etc.