Szukana fraza: [Abstract = "In Poland, the first attempts of colonization of cities took place in the 1950s in Warsaw and Kraków. During next decades Raven came back from centrum of cities and began colonized suburban zone, mainly big forests within the border of towns. Untilnow, Raven in Poland nest only in suburban zones. Observations of non\-breeding pairs inside of cities are still rare. The biggest population in cities do not exceed 20 breeding pairs."]