The history of ranges of the great tit (Parus major) and Japanese tit (Parus minor) in the Amur Region

The history of ranges of the great tit (Parus major) and Japanese tit (P. minor) in the Amur River basin is described on the basis of original data collected between 1970 and 2010 and published data. The main factor accounting for the expansion of the great and Japanese tits to the Amur basin and neighboring territories in the 19th to 21st centuries is economic activity, primarily agriculture and timber harvesting. The approximate range boundaries and the sympatry zone of these two species have been determined for the second half of the 19th century; the beginning, middle, and third quarter of the 20th century; and the turn of the 21st century. Three different ecological channels consecutively played the main role in the eastward expansion of the great tit: the Amur River valley (from the mid-19th to the early 20th century), the Trans-Siberian Railroad (since the early 20th century), and the Baikal-Amur Railroad (since the 1970s). It is shown that the concept concerning the finding of great tits in Udskii Ostrog by Middendorff’s expedition is erroneous: according to dates on the labels, the corresponding two specimens were in fact collected in a different geographic locality. It has been found that Komsomolsk-on-Amur is a new locality jointly inhabited by both species, independent of the main zone of their sympatry. It has appeared very recently, at the turn of the 21st century.