Do long-term changes in wing length indicate changes in migration distances of North Eurasian Passerines?

Abstract

Climate change affects the timing and the length of the migration routes of migratory birds. This can lead to evolutionary changes in body mass, length of wing and tarsus. In the present study, we examined changes in wing length over a time scale of nearly two centuries for six long-distance migratory songbird species nesting in northern Eurasia. Given that long-term bird ringing data are not available for these species, we compared data measured in recent years at the Baikal Bird Ringing Station with measurements of museum specimens collected between 1826 and 2010. A total of 446 museum specimens and 140 ringed birds were used for the study. Our results showed no significant change in wing length with the exception of Red-flanked Bluetail Tarsiger cyanurus (a decrease) and Olive-backed Pipits Anthus hodgsoni (an increase). This suggests that the results are similar to the results of other studies, where stable, increasing, and decreasing trends have been shown. Climate change may affect migration patterns, with more species becoming resident and with certain migration routes becoming shorter. In the latter case, migratory birds may also experience a reduction in wing length, and our results suggest that this may be the case in most Siberian Passerines. However, it should be taken into account that distribution ranges may also change, as breeding success increases and the climate becomes more favourable. Furthermore, birds nest further north, so the length of the migration route may not change. Therefore, their wing length does not necessarily change.