Recent bird studies across the boreal forest in Russia show that bird abundance is lowest in the center of the continent. About 4 out of 5 birds in the boreal forest are migratory. The migrants in the eastern end mostly winter in the tropics, while those in the western end winter in temperate areas, such as around the Mediterranean.
Geographic features south of the boreal forest probably cause these patterns of bird diversity. At the western end, high mountains and deserts, such as the Sahara and the Himalayas, deter migrants from reaching tropical wintering areas, whereas access to the tropics through eastern Asia is largely unimpeded.
In North America, the eastern boreal forest (New England, Maine, Great Lakes area) is more similar in climate, bird abundance, and migration strategy to the Russian far east than it is to Scandinavia, which is the traditional area for comparative studies.
This article summarizes the information in this publication:
Greenberg, R.S., Kozlenko, A., Etterson, M. and Dietsch, T. 2008. Patterns of density, diversity, and the distribution of migratory strategies in the Russian boreal forest avifauna. Journal of Biogeography, 35(11): 2049-2060.
Comparisons of the biotas in the Palaearctic and Nearctic have focused on limited portions of the two regions. The purpose of this study was to assess the geographic pattern in the abundance, species richness, and importance of different migration patterns of the avifauna boreal forest of Eurasia from Europe to East Asia as well as their relationship to climate and forest productivity. We further examine data from two widely separated sites in the New World to see how these conform to the patterns found in the Eurasian system.
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