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Factors Affecting Occurrence of Red-Backed Shrike (Lanius collurio) and Lesser Grey Shrike (Lanius minor) in Low-Intensify Agriculture Areas from Eastern Europe

Ajder V., Baltag E. S.

Polish Journal of Ecology

2017

Vol. 65, nr 2

285--294

Shrikes represent an important group of farmland bird species which inhabit open habitats where they prey on invertebrates and small vertebrates. Like the other farmland birds, shrikes are in the decline across their breeding range. During the 2014 breeding season, we conducted point observations in 470 locations in the Republic of Moldova, recording all the shrike individuals that were seen during 5 minutes. The highest density has been recorded for the red-backed shrike Lanius collurio, (0.489–0.652 breeding pairs ha-1) while for lesser grey shrike Lanius minor the density is ten times lower (0.042–0.076 breeding pairs ha-1). These two shrike species select pasture areas for breeding and avoid artificial surfaces, forests and wetlands. Regarding the geomorphological variables, red-backed shrikes and lesser grey shrikes prefer areas of a low, flat ground and aspects with low exposure to the sun radiation. According to the General Linear Model analyses, the red-backed shrike distribution is significantly influenced by percentage of arable land and orchards, while for lesser grey shrike we did not find any significant influence of environmental variables studied.

Intrapopulation variation of egg size in the White Stork (Ciconia ciconia) in Southern Poland

Profus P., Tryjanowski P., Tworek S., Zduniak P.

Polish Journal of Ecology

2004

Vol. 52, nr 1

75-78

White Stork (Ciconia ciconia) eggs were studied in Upper Silesia, Southern Poland. The measurements of eggs - their length, breadth, volume and elongation index were collected for 95 nests in years 1974-2002, and repeatability of these measurements was computed. Mean clutch size was 4.05 [plus-minus] 0.82. Mean egg measurements were: 72.10 [plus-minus] 2.18 mm, 52.19 [plus-minus] 1.47 mm, 100.49 [plus-minus] 6.92 cm^3 and 1.38 [plus-minus] 0.05, for length, breadth volume and elongation index, respectively. Coefficients of variation for clutch means ranged from 1.68 (breadth) to 4.37 (volume). Mean repeatability estimates were 0.53, 0.68, 0.63, 0.58 for length, breadth, volume and elongation index, respectively. The results obtained suggest that one should expect relatively low or intermediate heritability of egg dimensions in population studied.