(* = Kurzbeitrag)
Können Aaskrähen Corvus corone mit Gasballonen vertrieben werden?
(von 1994 bis 2006 vergeben)
Corvus corone, agricultural crops, damage, scaring, balloons
Landwirtschaft, Schäden, Ernteeinbussen, Nahrungsangebot, Ballone, Abwehrmethode, Verhalten
Corvus corone corone, Corvus corone cornix, Corvus frugilegus
Rabenkrähe, Nebelkrähe, Saatkrähe
Schweiz, Tessin, Mittelland
How effective are gas balloons in scaring Carrion Crows Corvus corone? The effectiveness of gas balloons as scaring devices against crows (mostly Hooded Crows C. c. cornix) was investigated on a waste dump in the canton of Ticino, Switzerland. The balloons were made of red latex, filled with helium to a diameter of 75 cm and were attached to nylon ropes of 20 m length. In two experiments on a study plot of 90 x 60 m it was registered where crows settled if (a) there were no balloons and (b) there were 3 balloons during 4 days. In both experiments the distribution of crows on the study plot changed markedly after the set-up of the balloons. On the first day with balloons no crows settled on the study plot (experiment A), or they were observed in the most distant parts relative to the balloons (experiment B). In the course of the four observation days with balloons, numbers of crows landing on the plot increased in both experiments. This was mostly the case in the areas more than 50 m away from the balloons. Hardly any crows were observed less than 30 m from the balloons. An inquiry by telephone including 34 farmers from the Swiss plateau indicated that balloons are effective against Carrion Crows (in this case C. c. corone) in agricultural land for at least 3 to 4 days. From these results and the observations on the waste dump we conclude that large gas balloons are suitable to scare crows from crops for a short time. If a long-term protection is needed, various scaring methods have to be applied alternately and combined.
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