Search for: [Abstract = "A Great Grey Shrike population was studied in two large plots \(220 km2 and 176 km2\) in western Poland in 1999 \- 2003. During the study period densities varied from 11.4 to 14.1 breeding pairs\/100 km2 but numbers were stable. In all, 180 Great Grey Shrike nests were found \- 114 \(63.3%\) in conifers, 66 \(36.7%\) in deciduous trees. This population’s reproductive parameters were relatively high in comparison to those of other European populations\: mean clutch size \- 6.6, hatching success \- 92.5%, mean brood size \- 5.72, mean number of fledglings per pair \- 4.1, mean number of fledged young per successful pair \- 5.25. Eggs \(mean 27.1 x 19.9 mm\) were found to be larger than reported in the literature. Nesting success was similar in both study plots, but there was slight seasonal variability\: 52.6% \- 41.0% from 99 nesting attempts in the first plot, 43.7% \- 42.1% from 37 nests in the second. Predation was the main cause of nest losses. Plastic string used as nesting material appeared to be the most important cause of partial failures\: 13 \(8.2%\) of a total of 147 nestlings surviving to fledging perished as a result of becoming tangled up in it. Nestlings rarely starved. Nests in linear habitats suffered significantly higher breeding losses \(78.6%, N = 28\) than those in non\-linear habitats \(50%, N = 90\). The high fitness values obtained from this population were probably due to traditional farming practices, the sparing use of pesticides and the good potential food base."]

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