Wyniki wyszukiwania - BazTech

Ograniczanie wyników

2 Polish Journal of Ecology

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: wrona siwa

Sortuj według:

Ogranicz wyniki do:

Long-term population trends of corvids wintering in urban parks in central Poland

Mazgajski T., Żmihorski M., Halba R., Woźniak A.

Polish Journal of Ecology

2008

Vol. 56, nr 3

521-526

Changes in the numbers of corvids wintering in Warsaw (Central Poland), in the last sixteen years were analyzed. Four species were studied: Rook Corvus frugilegus L., Jackdaw C. monedula L., Hooded Crow C. corone cornix L. and Magpie Pica pica (L.) The results were based on density data for birds foraging in three urban parks. The bird counts were conducted in November and December 1988.2003. It was found that the number of wintering Rooks decreased significantly (0.5 fold), populations of Jackdaws and Hooded Crows - increased (4.25 and 3.95 fold, respectively), and no apparent trends were observed for Magpies during this period. Observed trends for Rooks as well as comparisons of limited data gathered earlier in other areas may confirm suggestions about the changing of migration routes of this species.

The prey of hooded crow (Corvus cornic L.) in wetland: study of damaged egg shells of bird

Zduniak Piotr

Polish Journal of Ecology

2006

Vol. 54, nr 3

491-498

The species composition of the Hooded Crow (Corvus cornix) prey and its preferences for selected bird species are described on the basis of the egg shells found in the flooded area in the National Park "Ujście Warty" in Western Poland. In the years 2000-2003, during breeding seasons, 1104 shells of 16 bird species were found. The most common species was the Coot Fulica atra (69% of all the shells). The remaining species mainly were: the Mallard Anas platyrhynchos (13%), the Black-headed Gull Larus ridibundus (7%), the Black-necked Grebe Podiceps nigricollis (4%) and the Garganey Anas querquedula (4%). The number of shells found and the median date when shells were found differed between the years of study. The differences are probably related to the effect of variation in the number and differences in breeding phenology of potential crow's prey between seasons, which are connected with water conditions occurring in the study area.