@article{Polak_2010, place={Lund, Sweden}, title={Clutch and egg size variation in the Marsh Harrier Circus aeruginosus in eastern Poland}, volume={20}, url={https://journals.lub.lu.se/os/article/view/22638}, DOI={10.34080/os.v20.22638}, abstractNote={<p>The main aim of this study was to examine how clutch size and season influenced egg size in a population of Marsh Harriers <em>Circus aeruginosus</em> in eastern Poland. The Marsh Harriers nested in small, isolated patches of reed belts surrounding fish ponds. A total of 328 eggs from 70 clutches were measured during four nesting seasons (2005–2008). Average clutch size was 4.69 ± 0.71 eggs and did not vary between years; the modal clutch size was 5 eggs. Mean values of the egg dimensions were: egg length = 48.60 ± 1.78 mm; egg breadth = 38.36 ± 1.13 mm; egg volume = 36.53 ± 2.99 cm<sup>3</sup>. There was a strong correlation between egg length and egg breadth. The number of eggs in a clutch had no effect on the egg size.</p>}, number={2}, journal={Ornis Svecica}, author={Polak, Marcin}, year={2010}, month={Apr.}, pages={63–66} }