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ŠUMARSKI LIST 1-2/1981 str. 71     <-- 71 -->        PDF

Štromar , Lj. (1980): Ekološka analiza ornitofaune na području NE KRŠKO.
(Man.).
St ro mar , Lj. (1980): Masovna pojava sjenica plavetnih, Parus caeruleus L.,
zimi 1977/78. na području užeg dijela Zagreba. Larus 31, 209—214, Zagreb.


Bird Invaders


Summary


The authoress explains invasion as a variant in the migration phenomenon
of certain species of birds, She presents original observations and results on
the basis of foreign findings of the species Bombycilla garrulus which penetrated
Yugoslavia in a wide front in a heavy invasion during the exceptional winter of
1965/66 and spread towards the eastern Adriatic coast from Istra to Konavli.
The authoress has also devoted considerable attention to the investigation of
a large concentration of several hundred specimens of Parus caeruleus just outside
of Zagreb at Mirogoj. This took place during the winter of 1977/78 when Blue
Tits suddenly appeared on some Buxus sempervirens bushes and the disappeared
as suddenly as they had come. In earlier and later years, such large numbers of
Blue Tits had not ben observed although the signs of their presence were found.
In the same manner, a large group of several hundred specimens of the species
Pyrrhula pyrrhula which also belong to the group of invaders was studied. Parallel
investigations were carried out in the Krško Valley in the vicinity of NE Krško
and outside of Zagreb at Mirogoj during January 1980.


This bird migration variation has not been systematically investigated in
Yugoslavia but has heretofore been a peripheral study, for example in relation to
Bombycilla garrulus which attracts the attention of researchers by its periodic
appearances as a nester in the northern parts of Eurasia. That which remains
unknown concerning migration phenomenon would require planned studies.


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