Studies of ground-, shrub- and tree-nesting birds stress the importance of high nest losses as a factor influencing population dynamics. We conducted a two-season predation study with three field experiments, using artificial ground, shrub and tree nests simulating songbirds' nests as well as nests of ground-nesting galliformes and other tree-nesting birds. A portion of randomly selected nests have been monitored with camera-traps to identify predators. The results of predation experiments showed that predation rate on bird nests by the hooded crow depend on different environmental factors. In the first experiment near a city landfill site, where large numbers of crows were feeding, we didn't detect any case of nest predation by the hooded crow. It seems that crows are focused on feeding upon known sources of food at such locations. In the second experiment in the urban area predation increased markedly after exposure to artificial nests ranged from 30 to 100 % (predominantly by hooded crows – 79 % and Eurasian magpies – 18 % of predated nests), indicated that crows have detected (learned about) the increased food source in the area. In the third experiment artificial shrub and tree nests were set on different locations in open sub-urban landscape and exposed in short periods only (5 days) in order to minimize the potential learning of crows. Total predation rates by hooded crows in that experiment ranged from 25 % to 75 %.
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