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

Skórka P., Martyka R., Wójcik J., Lenda M.

Polish Journal of Ecology

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2011

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Vol. 59, nr 2

423-426

EN

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).

2

Supermarkets - a wintering habitat for House Sparrow Passer Domesticus L.

Skórka P., Lenda M., Skórka J.

Polish Journal of Ecology

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2009

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Vol. 57, nr 3

597-603

EN

Animals often co-exist with humans inside buildings, however in birds such cases are only sporadically noted. In this paper we describe the occurrence of House Sparrows in supermarket interiors. The probability of House Sparrows presence was higher in larger markets and during winter period. The abundance and density of birds were positively and negatively related to the size of the supermarket, respectively. The birds were active at night. They foraged mainly along market shelves on bakery products, vegetables and cereals. We did not observe nesting inside market halls. The supermarkets seem to be hospitable wintering place for this species, however they may also be ecological traps imprisoning the birds once they find their way in. Moreover, House Sparrows may contaminate food, thus, the presence of such species inside supermarkets should be controlled.

3

Oviposition patterns in the myrmecophilous butterfly Maculinea alcon denis & schiffermüller (Lepidoptera: Lycaenidae) in relation to characteristics of foodplants and presence of ant hosts

Nowicki P., Witek M., Skórka P., Woyciechowski M.

Polish Journal of Ecology

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2005

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Vol. 53, nr 3

409-417

EN

To test the hypothesis of random oviposition by Maculinea butterflies we investigated the oviposition patterns of M. alcon Denis & Schiffermüller in wet meadows in the Vistula valley, southern Poland, in relation to the stem length and flower number of Gentiana pneumonanthe Linnaeus foodplants as well as to their spatial distribution, the height of the surrounding vegetation and the presence of potential ant hosts. Analysis conducted for 403 gentians recorded within the 0.96 ha study plot indicated that plants with M. alcon eggs present were significantly higher and had more flowers. On the other hand, neither the local density of gentians nor the presence of ant hosts had any apparent effect on oviposition preferences of M. alcon. Our conclusion is that females of the butterfly select visually conspicuous plants as the oviposition sites regardless of their clumping or ant presence. As a consequence, the two factors do not need to be included in computer models developed to study the population dynamics of the species and its trophic interactions with foodplants and ant hosts.

4

Jacquard and harness woven fabric designing using CAD-CAM system

Krawczyńska I., Skórka P.

Zeszyty Naukowe. Włókiennictwo / Politechnika Łódzka

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2000

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z. 58

233-240

EN

High labour consumption in converting artlstlc designs into technical drawings and then into pattem cards considerably prolonged the process of implementing new pattems into industrial practice. The development of industrial pattem-designing, both in quantity and quality terms, required the adoption of new methods to accelerate this proces s and to reduce the costs of design conversion into technical drawings (which in some cases could be avoided) followed by pattem cards preparation.