The periodic irruptions of Rose-coloured Starling are driven by drought and hence variation in the availability of their preferred prey species - grasshoppers and locusts. These irruptions typically start in spring and early summer, when birds return from their Indian wintering areas and find that their food supply has failed. The largest irruptions into Western Europe occured in 1853, 1907-1909, 1925, 1932 and 1948 and 2002. During these irruptions the species often settles down to breed in huge numbers in Eastern Europe. Most spectacularly of all, in 1875, 6000-7000 pairs nested in the ramparts of a castle in northern Italy; yet this species was unrecorded in the entire country for the following 33 years!
Alex
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Dr Alexander C. Lees
Lecturer in tropical ecologyManchester Metropolitan University
Lab Associate
Cornell Lab of Ornithology,
Cornell University
http://www.freewebs.com/alexlees/index.htm@Alexander_Lees