Current and retrospective numbers of anseriform birds in autumn migration in the Selenga River delta (Republic of Buryatia, Lake Baikal)
I. V. Fefelov1, Yu. A. Anisimov2, A. I. Povarintsev1
1Irkutsk State University, Irkutsk, Russia
2Baikal’sky State Nature Biosphere Reserve, Tankhoy, Russia
Keywords: waterfowl, Selenga delta, migrations, number dynamics
Abstract
After results of autumn counts of waterfowl in the Selenga delta in 2018-2020, their recent numbers during the autumn migration were estimated, and its comparison to results of analogous intensive censuses in 1989-1995 was carried out. The decreasing of numbers and percentages was found in some duck species (Northern Pintail, Eurasian Wigeon, Northern Shoveler, and Pochard); these parameters are rather stable in Mallard. Data on stopover longevity obtained in other regions of the world in the last time let us to give more precise retrospective estimates for numbers of waterfowl having visited the Selenga delta during autumn migrations in the 2nd half of 1980s and the 1st half of 1990s. More adequate numbers of stopping birds in the period mentioned above are 0.5-1.1 million individuals per season (at least, not less) instead 2-5 million being proposed formerly. In the present time, the lower number limit for ducks having visited the delta per autumn season obviously appears to be 0.3 million individuals; intensive counts during all autumn migration are necessary to set the upper limit. Numbers of waterfowl are approximately twice less now than 30-35 years ago. Causes of their decrease need to be sought outside the Selenga delta, probably in the general situation in regional and trans-regional geographical populations. The delta prolongs to support more than 1 % of the East Asian geographical population of Pochard, which recently got the status “Vulnerable” in the IUCN Red List. The nature refuge “Kabansky” plays the much important role as the no-take zone for waterbirds during autumn hunting seasons.
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