Dr. Tóth Sándor (szerk.): A Bakonyi Természettudományi Múzeum Közleményei 3. (Zirc,1984)
KEVE ANDRÁS: Adatok a Balaton és környéke madárfaunájához (Aves)
centuary to give a positive basis for the question of "harmfulness and usefulness" of birds, in an ecological concept and with the help of analyses of the stomach-contains to show the real relations between hirds and other animals. During the Balaton-research in 1941 we have collected a good material and it was plainned that VASVÁRI should examine this, but his tragic circumstances prevented him in doing so. Also those stomach-contains collected near the Balaton before -1941, were selected by HEGYMEGHY, but unfortunately all of the were destroyed during the ware /see the literature also/. In the present study I donot want to treat the analyses of stomach contains. There are some materials which are due to the quick digestion of the birds undeterminable, e.g. Earthworms, Slugsm etc. It remained the observation, but the older ones mad<= by hunters, agronomits , fishers, etc, were often so superficial and led to so many erraneous and generalized conclusions, that at the end of last centuary was the correct oppinion that positive data can be furnished only by the stomach-contains. But a Buzzard on a deaded hare cannot prove that 3uzzards kill hares; confounding Gulls with Terns resulted in the belief that the Gulls are fishing under waterlevet etc. Even some contains of stomach, which are secondary can give erraneous results, e.g, snail in a Peregrine Falcon, etc., and show that in the bromatology observations are not superfluous, especially in our times, where collecting for such pourposes is difficult in due to nature-presevation . But it must be well controlled and I must point out that observation is only a complementary method in the bromatology. The well controlled observations are not easy. As example I can mention the House Sparrow /Passer domesticus/. We can see them often picking up something, but it is difficult to prove what, or we can often flush a flock of Starlings /Sturnus vulgaris/ from a maiz-field, but what are they doing there? Opening + he stomachs of Starlings shot when flying out'from the field, they were empty /SZIJJ7 . The food of many bird species is already known, it is also known that wualitative altenations are caused in it by the rapid environment changes, e.g. Rook, Turkish Dove /REKASI/. To these researches observation is a good supplement. By these observations we can get data, how the animal and plant communities are in relationship, not only which species, but also how, and this is the real duty of bromatology. During my studies of 35 years near the Balaton Lake I could make some true observations also on the feeding of birds. I have partly published in my faunistic papers, now I try to give a summarized account on them. Sorrily the stomach-contains of Diving, of Shorebirds etc, collected in 1941 were burnt unpublished. In these we have always found snails /especially Lithoglyphus/ and shell /especially Dreissena/ , but it was not possible to certify whether the birds had eaten them alive or only the shells or valves. The researches on the Bodensee /SZIJJ, etc./ make it problematic whether the number of Goldeneyes and Tufted Ducks was lower before 1934, when the gradation of Dreissena has begun. LOVASSY /1897/, KELLER /1934, 1935/ and H0 M 0NNAY /1940/ have written too generalized on these Ducks and have not given numerical data, so it is not possible to make a comparison. On the contrary in the case of the Coot one can well nee that the autumn- concentration of Coot-masses is due to the fact that the beach of Keszthely gets mudy , more correctly becouse of the mud following reed-grass /L0VASSY, 1924/. In an other paper I have show /1972/ that there are some problems , where the Coot is a good indicator. Now that the number of Dreissena diminished we shall see, wether the Diving Ducks will also diminish? The data on the feeding-observations on single species are of interest in the researchwork of the Balaton and they are far from a conclusion, therefore I give them only in Hungária. Perhaps I can mention some special examples, so the BeeEaters have fed only with colourful insects, like great Dragonflies and Humbles /Xylocopa/ ; the Syrian Woodpecker likes almonds and apricotestone s ; the Hooded Crow has eaten often crawfisches /Leptodactylus/ and fiches /Alburnus/, so does the Golden Oriole too. Great Til and Crossbill feed on Sunflowe-seeds . I have seen a Hooded Crow on the back of a pig, Starling on Buffaloes, etc.
