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Spatial segregation of foraging sites in winter mixed-species flocks of forest birds near seoul, Korea

Lee Sang-don, Jabłoński Piotr G.

Polish Journal of Ecology

2006

Vol. 54, nr 3

481-490

The wintering mixed flocks of tits (Paridae) and associated birds, are good objects for studying ecological niche division. In this respect the mixed species flocks on the Asian continent are poorly studied in comparison to European and North American ones. In this report we describe spatial distribution of foraging sites of eight bird species in 39 winter flocks near Seoul, Korea: Varied tit - Parus varius Temminck & Schlegel, Great tit - P. major Temminck & Schlegel, Marsh tit - P. palustris Bianchi, Coal tit - P. ater Buturlin, Long-tailed tit - Aegithalos caudatus Clark, Nuthatch - Sitta europaea Swinhoe, Japanese Pygmy Woodpecker - Dendrocopos kizuki Taka-Tsukasa, and Goldcrest - Regulus regulus Blakiston. Foraging sites (in coniferous and mixed forests) were classified into five height layers: on the ground, <1.5 m above the ground, 1.5-4 m, 4-7m, and > 7m. Trees were divided into three horizontal zones depending on the distance from trunk: crown interior, intermediate zone, and external twigs. Species differed significantly in the use of height layers: P. major foraged mostly on the ground, P. ater and A. caudatus foraged mostly in the highest forest layer, P. palustris was often seen in bushes, and P. varius occurred in the middle tree layer. There was no clear correlation between height of foraging and species body size. However, body size played an important role for segregation in horizontal zones, and two species, the larger P. major and the smaller P. ater differed significantly in the mean distance from trunk. Species of large body size like P. varius and P. major, foraged mostly in the interior of the tree crown, while the smaller species, P.ater and A. caudatus, foraged mostly in the external zone; the intermediate in size, P. palustris, foraged equally often in each of the three zones. The sites used most often by Korean populations of three tit species, P major, P. palustris and P ater, were similar to the sites used by European populations of the respective species. These results represent one of a few quantitative studies on mixed species flocks in continental Asia.

Individuals adjust their body reserves to dominance position within mixed flocks of the willow (Parus montanus) and the crested tit (P. cristatus) : a field experiment

Krams I.

Polish Journal of Ecology

1998

Vol. 46, no 2

207-216

Mixed-species flocks represent a prevalent sociality form of the forest wintering parids. Efficient use of time is of high survival value for individual foragers. It was found that in groups composed of willow (Parus montanus) and crested tits (P. cristatus) intraspecific competition appears to be more severe than interspecific interference. Decreasing time allocated to intraspecific aggressiveness, social individuals in mixed-species flocks supposedly increase their probability of survival till the next breeding season. Social dependence of the two tit species was controlled by observations of their fattening strategies.Willow tits were considered to substitute for the lacking crested tits, since replacement of their metabolized energy was found to be dependent on the influence of dominant crested tits.