@misc{Skórka_Piotr_Population_2005,
 author={Skórka, Piotr and Wójcik, Joanna D and Polska Akademia Nauk. Muzeum i Instytut Zoologii},
 editor={Museum and Institute of Zoology, Polish Academy of Sciences},
 copyright={Rights Reserved - Free Access},
 address={Warszawa},
 howpublished={online},
 year={2005},
 language={eng},
 abstract={Density and behavior of the Mistle Thrush occurring in the Niepołomice Forest (southern Poland) and adjacent open areas were studied during the winters of 1996/1997, 1998/1999 and 2000/2001 (December–February). Mistle Thrush densities differed significantly between winters. Abundance of thrushes decreased with winter progression. Bird density and mistletoe clump density were positively correlated. Birds held territories or grouped in flocks. In the forest, flocks were observed only during the winter 1996/1997 when the largest density of birds was noted. Flock size decreased throughout winter, but, simultaneously, the number of territorial birds was stable. It suggests that at the end of the winter 1996/1997 some birds from flocks started to hold territories. Bird flocks were observed also in open areas and they preferred to feed in pastures. In the forest, every individual territory consisted of several clumps of mistletoe on a few trees standing close together. Birds defended mistletoe clumps against conspecifics and also other species (Pyrrhula pyrrhula, Turdus merula, Dendrocopos major). Aggressive encounter rate was positively correlated with bird density and negatively with winter progression (winter progression was correlated negatively with berry supply), but surprisingly was not correlated with mistletoe clump density and temperature. It is possible that during years with high berry supply, the density of birds may be so large, that defending fruits against many neighbors may be too costly and less profitable than feeding in flocks.},
 type={Text},
 title={Population dynamics and social behavior of the mistle thrush Turdus viscivorus during winter},
 volume={40},
 number={1},
 journal={Acta Ornithologica},
 publisher={Museum & Institute of Zoology},
 keywords={Mistle Thrush,, Turdus viscivorus,, aggressive behavior, flocking behavior, fruit defense, mistletoe, Niepołomice Forest},
}