LONG-TERM POPULATION TRENDS OF CORVIDSWINTERING IN URBAN PARKS IN CENTRAL POLAND

摘要

Changes in the numbers ofcorvids wintering in Warsaw (Central Poland), inthe last sixteen years were analyzed. Four specieswere studied: Rook Corvus frugilegus L., JackdawC. monedula L., Hooded Crow C. corone cornix L.and Magpie Pica pica (L.) The results were basedon density data for birds foraging in three urbanparks. The bird counts were conducted in No-vember and December 1988-2003. It was foundthat the number of wintering Rooks decreasedsignificantly (0.5 fold), populations of Jackdawsand Hooded Crows - increased (4.25 and 3.95fold, respectively), and no apparent trends wereobserved for Magpies during this period. Ob-served trends for Rooks as well as comparisons oflimited data gathered earlier in other areas mayconfirm suggestions about the changing of mi-gration routes of this species.