The current status of Asian populations of the Horned Grebe Podiceps auritus (Aves: Podicipediformes) in Russia

The author presents the results of analysis of the current status of Asian populations of Horned Grebes Podiceps auritus (L.) based on his own studies and the published data. This work is part of the preparation of the next edition of the Red Data Book of the Russian Federation. The state of the world Horned Grebe population had not caused concern for many years, but in 2015, the Horned Grebe was included in the IUCN Red List of Threatened Species and assigned the VU (Vulnerable Species) category because of a rapid decline in the species' numbers in North America and Europe. Despite the voluminous published data on the Horned Grebe, precise information on the species' population dynamics in some regions of the Russian Federation is very scarce. A few publications feature estimated numbers achieved by extrapolation of the species' density data, but usually the authors would just give grade definitions like "common", "numerous" or "rare". Therefore, our quantitative estimation of the Horned Grebe breeding population in the Asian part of Russia is quite rough: 30-60 thousand pairs. The species' breeding area in that territory is about 6.6 million km or 25% of its world range area. Presuming that the species breeds with the same average density (5-9 pairs / thousand km2) in the rest of its range as in the Asian part of Russia, we may estimate the world Horned Grebe population at the same numbers as in the IUCN Red List of Threatened Species (Version 2016-3) (239-583 thousand individuals). The largest species' resources are located in the Trans-Urals and the western part of Western Siberia (Kurgan, Tyumen, Omsk regions and the Khanty-Mansiysk autonomous okrug). Eastward of that territory the abundance of the Horned Grebe reduces significantly. The few data on the species' population dynamics in the Trans-Urals and the western part of Western Siberia show that the population in that area decreased by 70% over the last two or three decades. Those regions are now breeding grounds for more than a half of the Asian population of the Horned Grebe in Russia (16-36 thousand pairs). The average species' density there is 14-36 pairs / thousand km2. As for the vast territory of Eastern Siberia and the Far East featuring mostly mountainous landscape, the Horned Grebe is very rare there (probably due to insufficiency of breeding habitats) and nests with a much lower density (1-3 pairs / thousand km2) while its total numbers in that area are 7-15 thousand pairs. Some breeding areas of the species observed for a relatively long period of time also show a negative trend in the population abundance. All these data provide sufficient grounds for governmental protection of the species and its inclusion in the Red Data Book of the Russian Federation. However, it is necessary to point out the widespread decrease in the species' numbers even in areas with no anthropogenic activity which shows that the reasons behind the abundance reduction are global and have not only been anthropologically induced. Possibly, there are other factors affecting the species' migrations and wintering. Priority measures for the species protection are conservation of breeding habitats, particularly restriction of forest felling and fish farming around forest lakes. The article contains 1 Table, 107References.

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