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The effect of urbanization on the diet composition of the Tawny owl (Strix aluco L.)

Grzędzicka E., Kus K., Nabielec J.

Polish Journal of Ecology

2013

Vol. 61, nr 2

391--400

In recent years, developing urban areas have affected food abundance and the feeding grounds of birds. The article contains analysis of the Tawny owl’s diet during four years (2006–2009) from different types of the urbanized area: city, town (much smaller than city) and countryside – based on 356 pellets with 726 prey items. The main group of victims was Rodentia, common were also Apodemus agrarius and Apodemus sylvaticus. Other important groups in the diet were: Microtidae (especially species Microtus arvalis) and Aves. As a generalist, Tawny owl fits the diet to the actual resources in a very flexible way. The main goal of the present work was to describe the food composition variability of the Tawny owl along with the degree of urbanization. Percentages of Microtus arvalis, Micromys minutus, Talpa europaea depended on the urbanization level, while Apodemus flavicollis, Insecta and Amphibia were related to the distance to nearest city centre. The study has shown that the diet of the Tawny owl has been changing along the urbanization gradient. It confirms earlier findings on high plasticity of foraging of this species in urbanized landscape.

Residual stresses and shape memory effect

Breczko T., Kus K.

Transactions of the Institute of Fluid-Flow Machinery

2001

nr 108

33-45

It is possible to estimate the reliability of the materials during their use by recording the changes in defect density of polycrystalline structure, which can be estimated on residual stresses at a crystal nufactured using shape memory alloy (SMA) are presented. The experimental data are based on the investigation of the changes in the root-mean-square (RMS) micro-strains and size of coherent block in the SMA caused by thermal and mechanical loading. The study is performed on the samples of aproximately equiatomic TiNi alloy. To induce the reversible martensite transformations in the material the external loading is applied with subsequent data recording using the X-ray method. The results of experimental measurements of the RMS microst rain and coherent block size in austenite are presented. Basing on the experimental data a modified (by Brechko [4-5]) mathematical model of Likhachev and Malinin [3] is proposed, which is used in the computer simulations including the martensite transformations, twining, elastic and irreversible deformations. The experimental and computer modeling results of stress and strain field generated by the defect in polycrystalline materials are discussed.