Black kites of the nominal subspecies Milvus migrans migrans breed in the Western Palearctic and in Central Asia, while the European population is relatively small. The birds winter mostly in sub-Saharan Africa. Until 2000 winter observations of black kites were rare in Greece, and also within the tri-point border area of Austria, the Czech Republic and Slovakia. At that time regular wintering of black kites started there. These data and evidence from recent local literature as well as from a number of unpublished data obtained throughout European countries and reviewed in this paper corroborate the impression that numbers of black kites wintering in Europe and the whole Mediterranean area including Turkey are increasing. The reasons considered are climate warming in the area and some negative changes in sub-Saharan Africa in the traditional wintering grounds of black kites. Notes about the wintering of black/red kite hybrids are also added.
Tree species composition of Central European alluvial hardwood forests has changed with the arrival of flood-intolerant and mesic species. Within this group of tree species, a dominant role is played by field maple (Acer campestre) and European hornbeam (Carpinus betulus). This study was performed in the Lanzhot natural forests at the confluence of the Morava and the Dyje Rivers, which are considered to be one of the most natural alluvial hardwood forests in Central Europe and where the absence of the direct influence by humans for 75 years has allowed spontaneous development. Our basic research questions were as follows: (1) does the mutual proportion and structure of field maple and hornbeam populations change along an elevation gradient of 4 m in an alluvial forest and (2) does the tree spatial pattern of field maple and hornbeam change along this gradient? The study found significant differences in the development of hornbeam and field maple populations with increasing elevation in an alluvial hardwood forest. While the strength of the hornbeam population clearly increases with increasing elevation, the field maple population does not. Compared to hornbeam, field maple is closer to the r-strategy side of the K-r continuum on alluvial sites. Our study reveals that field maple and hornbeam are mainly distributed in clusters on alluvial sites. Both species are concentrated at places with lower flooding intensity, i.e. to higher elevation sites. The study shows that tree spatial patterns could change dynamically along a short elevation gradient in alluvial hardwood forest.
The paper deals with the issue of the spontaneous development of Central-European Xoodplain forests. The research object was the Cahnov-Soutok National Nature Reserve situated on the conXuence of Dyje R. and Morava R. in the Czecho-Slovak-Austrian borderland area. This locality has been left to spontaneous development since the beginning of the 1930s. In the years 1973, 1994 and 2006, the surveyed site was subjected to the measurement of standing and lying, live and dead trees reaching a diameter at breast height of 10 cm and the whole area regeneration of woody species. The work objective is to describe the most pronounced trends in tree layer changes having occurred in the period of study and to capture changes in the total tree volume and production of dendromass during the disintegration of the old grazing oak layer. The survey into the near-natural Xoodplain forest of Cahnov-Soutok showed that (1) the most signiWcant trend is a decreased representation of Quercus robur in all monitored indicators and conversely an expanding representation of Acer campestre, Carpinus betulus and Tilia cordata and (2) that the Xoodplain forest ecosystem demonstrates a highlevel stability in the total volume of tree biomass with an essential change in the tree species composition, spatial structure and average stem volume of individual trees.
We characterized the spatiotemporal activities in winter grounds of the tagged Red Kites Milvus milvus originated from Austria, Czech Republic and Slovakia and wintering in southeast Europe. Birds arrived to winter grounds in Hungary, Croatia, and Greece from 10 July to 12 December (median 22 October) and departed from winter grounds between 14 February and 22 May (median 14 March), thus staying at winter grounds from 121 to 229 days (median 145, mean 161±43 SD). If we regarded kernel density estimate 80% (area of main foraging and roosting activities) as the best indicator as to the size of home range, we revealed that the size of a home range for Red Kites staying at one place through the entire winter was from 10 to 108 km 2 (median 72, mean 60±36 SD) and that the size of home range for birds with local shift(s) in winter grounds was from 344 to 620 km 2 (median 434, mean 466±115 SD). We found not only Red Kites at these places but often also Black Kites Milvus migrans. The numbers of Black Kites wintering together with Red Kites were higher than the number of Red Kites at all Greek winter grounds. At winter grounds in Hungary and Croatia, the number of Black Kites was lower than the number of Red Kites or Black Kites were wholly absent. Sympatric occurrences according to only direct observations of wintering Red and Black Kites were found also in some other locations in Bulgaria, Croatia, Greece and Hungary.
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