Influence of Age on the Flushing Distance of Marked and Unmarked Black-Billed Magpies

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Abstract
Effect of age on the distance at which Black-billed Magpies Pica pica flush from an approaching observer was studied in an urban area. Handling for banding purposes had no significant effect; banded and unbanded magpies showed no differential sensitivity to observer approach. Juveniles tolerated closer approach than adults. Between the ages of 1 and 5 months, the distance at which juveniles took flight in the face of an approaching observer increased significantly. Among adults, the flushing distance increased steadily up to the age of 3 yr, but was constant thereafter. Younger birds probably learned from older birds to avoid the danger of being approached too closely by the observer.