Small-scale differences in the breeding ecology of urban and rural Magpies Pica pica

Abstrakti

This study tested if urbanisation had small-scale effects on Magpie reproductive biology. It was carried out in 1999-2000 in Sofia, Bulgaria, where one of the highest Magpie population densities known is found. Breeding parameters were compared between an urban area and its rural surroundings extending 1 km out of it. Magpies in the urban area laid significantly earlier than those in the rural area. Clutch size and egg volume were similar between the two habitats. Fledging success was significantly higher in the urban area. Predation accounted for more losses in rural habitat while failures due to infertility and addling were more frequent among urban Magpies. Predation was higher at the egg stage than at the nestling stage, and this trend was more pronounced in the rural area. The probability of breeding success was significantly higher in the urban area due to lower predation most likely as a result of proximity to human activity. Urban birds, however, suffered more brood reduction and thus produced fewer fledglings per successful pair compared to rural pairs.