Andrzej Węgrzynowicz
Ornis Polonica 2013, 54: 12–24
https://doi.org/10.12657/ornis.2013.1.1
Abstract: In 2008–2009 the breeding Magpies and Hooded Crows were surveyed in 19 study plots (291 ha) in housing estates and parks in Warsaw. Additionally, the variables of nest location were compared between both species and several factors potentially affecting their densities and changes in their abundance were considered. Hooded Crows were more abundant in parks (mean 5.0 pairs/10 ha), whereas Magpies predominated in housing estates (4.3 pairs/10 ha). In order to determine the changes in the Magpie and Hooded Crow abundance, these results were compared to the data from 1970s and 1980s collected in the same study plots. The number of the Magpie increased 5–6-fold and time course of these changes was diverse in different habitats and city zones. The population of the Hooded Crow increased 9-fold. The similarity of nest location of both species was rather low, however, weak negative correlation between densities of Magpie and Hooded Crow was found. It was hypothesized that high densities of the Hooded Crow influenced nest-sites choice, occurrence and changes in abundance of the Magpie. High ecological plasticity revealed by the Magpie allows it to sustain in areas heavily populated by the Hooded Crow.
