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1

The comparative osteology of the humerus in European thrushes [Aves: Turdus] including a comparison with other similarly sized genera of passerine birds - preliminary results

100%
Wojcik J. D.
Acta Zoologica Cracoviensia
|
2002
|
tom 45
|
nr Spec.issue
2

Population dynamics and social behavior of the Mistle Thrush Turdus viscivorus during winter

63%
Skorka P., Wojcik J. D.
Acta Ornithologica
|
2005
|
tom 40
|
nr 1
35-42
The density and behavior of the Mistle Thrush in Niepołomice Forest (southern Poland) and adjacent open areas were studied during winter (December-February) in 1996/97, 1998/99 and 2000/01. Mistle Thrush densities differed significantly from winter to winter, and the abundance of thrushes decreased as the season progressed. Bird density and mistletoe clump density were correlated positively. Birds held territories or congregated in flocks. The latter were sighted in the forest only during winter 1996/97, when the largest density of birds was noted. Flock size decreased progressively during that winter, but at the same time, the number of territorial birds remained stable. This suggests that by the end of the winter 1996/97 some birds from the flocks had begun to hold territories. Flocks were also seen in open areas, and displayed a preference for foraging on pastureland. Each individual territory in the forest consisted of several clumps of mistletoe on a few adjacent trees, which were defended against both conspecifics and other species such as Pyrrhula pyrrhula, Turdus merula and Dendrocopos major. The aggressive encounter rate was correlated positively with bird density but negatively with the progress of winter (the latter was correlated negatively with the berry supply). Surprisingly, it was not correlated with mistletoe clump density or temperature. During abundant berry years, the density of birds may have been so large that defending the fruit against numerous neighbors would have been energetically less profitable than communal foraging.
3

Walory ornitologiczne okolic Rozkochowa - propozycja ochrony

63%
Skorka P., Wojcik J. D.
Chrońmy Przyrodę Ojczystą
|
2000
|
tom 56
|
nr 5
99-111
4

Winter bird communities in a managed mixed oak-pine forest [Niepolomice Forest, Southern Poland]

63%
Skorka P., Wojcik J. D.
Acta Zoologica Cracoviensia
|
2003
|
tom 46
|
nr 1
Winter bird communities in a managed mixed oak-pine forest (Niepołomice Forest, southern Poland) were studied during winters the 1996/1997, 1998/1999, and 2000/2001 using the line-transect method. The transect (9.5 km long, 100 m wide) was conducted through three habitats: forest edge, mature, and young stands. The authors noted 5,764 individuals within the transect belonging to 33 bird species. The largest number of species was noted in mature stands – 27 (mean density: 34.0 inds/10 ha), then at the forest edge – 24 (19.4 inds/10 ha), and 18 species in young stands (25.2 inds/10 ha). The density of birds varied between winters and decreased during their course. The density of plant-eaters was significantly lower than that of invertebrate-eaters, but the total biomass of these groups did not differ. Plant-eater biomass was significantly higher in mature stands and at the forest edge than in young stands. Invertebrate-eater density was considerably lower at the forest edge, but the biomass of this trophic guild did not differ significantly among habitats. Plant-eater biomass was significantly lower during winter 1998/1999 and it is supposed that this variation in plant-eater density affects the most total variation in bird communities in the Niepołomice Forest. The authors’ results indicate that old stands are probably the most favourable habitat for some small birds in winter.
5

Species richness of breeding birds at a landscape scale: which habitat type is the most important?

51%
Skorka P., Martyka R., Wojcik J. D.
Acta Ornithologica
|
2006
|
tom 41
|
nr 1
6

Laki kolo Podleza - atrakcyjny ornitologicznie teren w poblizu Krakowa

51%
Skorka P., Wojcik J. D., Musialek R.
Chrońmy Przyrodę Ojczystą
|
2003
|
tom 59
|
nr 1
122-126
7

Wystepowanie puszczyka uralskiego Strix uralensis w Lasach Radlowsko-Wierzchoslawickich kolo Tarnowa

51%
Wojcik J. D., Skorka P., Martyka R.
Notatki Ornitologiczne
|
2000
|
tom 41
|
nr 3
257-259
8

Site parameters’ variance – a missing dimension in the studies of nest-site selection?

51%
Skorka P., Martyka R., Wojcik J. D., Lenda M.
Polish Journal of Ecology
|
2011
|
tom 59
|
nr 2
In most studies of nest-site selection the data of habitat parameters are treated with analysis of variance. A basic assumption of this test is the homogeneity of variance. Here, we show that the nest-site selection process leads to lower variance of the selected parameters than in the case of random points which generally describe the available average characteristics of the environment. Thus, the variance should be accounted for in studies on nest-site selection and it should be treated not as a problem (as it is usually done), but as a source of additional important information on the selection process. Comparison only of mean values often does not lead to significant differences between nest site parameters and random points which may result from a small effect size (when animals select features similar to the general mean of available characteristics). Deeper insight into variance of the site parameters may elicit important results. We illustrate this issue with real data on nest site (islets and shores of water reservoirs) selection in the Common Gull Larus canus. Four (islet’s area, vegetation height on islets, vegetation cover on shore and distance to nearest shrub or tree on shore) from eight parameters were favored by the birds and, as predicted, their variance values were lower than of those not selected (vegetation cover on islets, distance of the islets to shoreline, vegetation height on shore and distance to water).
9

Ptaki Ziemi Tarnowskiej

51%
Martyka R., Skorka P., Wojcik J. D., Majka K.
Notatki Ornitologiczne
|
2002
|
tom 43
|
nr 1
29-48
10
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Wystepowanie kraski [Coracias garrulus] w Malopolsce

51%
Wojcik J. D.
Kulon
|
1998
|
tom 03
|
nr 1
47-55
11

Habitat and nest site selection in the Common Gull Larus canus in southern Poland: significance of man-made habitats for conservation of an endangered species

45%
Skorka P., Martyka R., Wojcik J. D., Babiarz T., Skorka J.
Acta Ornithologica
|
2006
|
tom 41
|
nr 2
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