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Effect of weather change on flock size of the Snow Bunting (Plectrophenax nivalis L.) wintering in south-western Poland

Orłowski Grzegorz, Gębski Paweł

Polish Journal of Ecology

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2007

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Vol. 55, nr 1

181-185

EN

In winter 2004/2005 some exceptionally large (on the Central European scale) concentrations of Snow Bunting (Plectrophenax nivalis), up to 1600 individuals, were recorded in Lower Silesia (south-western Poland). The Snow Bunting flock size was positively correlated with the mean daily air temperature (P = 0.002). The average flock size during snowless days was 11 times higher than in the snowy period (P = 0.0017). One of the factors encouraging the more abundant wintering of Snow Bunting in Central Europe may be the milder climatic conditions, especially higher temperature and lack of snow cover. During the last four decades the rise of mean temperatures and shrinking of the snow cover period in winter months (December-February) have been observed in Lower Silesia.

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High juvenile mortality of grass snakes Natrix natrix (L.) on a suburban road

Ciesiołkiewicz Joanna, Orłowski Grzegorz, Elżanowski Andrzej

Polish Journal of Ecology

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2006

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Vol. 54, nr 3

465-472

EN

Hundred-ninety dead grass snakes Natrix natrix (L. 1758) were collected over 10 months in two years on an 1800-meter stretch of a local road in the outskirts of Wroclaw, a major city in SW Poland. The mortality rate reached a record high value of 204 snakes km^-1 year^-1 (1.16 snakes km^-1 day^-1). Two peaks of road mortality, one from the end of May through the beginning of June, and the other, at the beginning of August, contributed 80% of records. The majority (89%) of 110 measured specimens were juveniles with the total length below 30 cm, and around 30% of those collected in the spring and the summer were hatchlings with the total length up to 20 cm. This suggests a significant extension of the hatching period, which may be related to the local mild climate and/or climate warming. The road kill numbers correlated significantly with maximum daily temperatures through the cool (for May) to average (for June) spring of 2004 but not through the hot spring of 2003, which suggests that under average or cool weather conditions the mobility of grass snakes is limited by maximum daily temperatures. No significant correlation with daily rainfall could be established.

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Factors influencing mammal roadkills in the agricultural landscape of South-Western Poland

Orłowski Grzegorz, Nowak Lech

Polish Journal of Ecology

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2006

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Vol. 54, nr 2

283-294

EN

The aim of the present study was to determine the yearly mortality level and identify the collision places of mammals on a road network with varying traffic volume, as well as to establish the main relations between habitat structure and the number of roadkills. During 26 months of survey on a 48.8 km road network (15 roads) with different traffic volumes (350-10500 cars per 24 h) situated in an agricultural landscape of SW Poland 383 killed mammals of 23 species were found. The most abundant group were small rodents (40%), with dominant common vole Microtus arvalis (26%) followed by insectivores (32%), topped by two species of hedgehogs Erinaceus spp. (20%). The average ([plus or minus] SD) road-kills index during the whole study period on 11 road sections with the lowest traffic volume (350-460 cars per 24 h) amounted to 0.29 [plus or minus] 0.14 (range = 0.08-0.56) casualties per 100 m. This value was over seven times lower than on the section with the highest (10500 cars per 24 h) traffic volume (2.13 casualties per 100 m). Over 80% of victims were found between May and October. During the whole study period 38% of victims were recorded within built-up areas, where 26% of the studied roads were localized. The other 62% were found on the roads situated in the open farmland (74% of all roads). The clear majority of hedgehogs Erinaceus spp., weasels Mustela nivalis, brown rats Rattus norvegicus, beech martens Maries, foina and red foxes Vulpes vulpes died within villages, while the animals killed on roads in the open farmland included all recorded common voles, moles Talpa europaea and common shrews Sorex araneus. The decisive factor affecting the mortality level in mammals in the multiple regression model was the daily vehicle traffic volume. This variable had significant, positive influence on the number of victims both within the most abundant species, their groups (insectivores, rodents, mustelids), as well as all mammals. The road location in the open countryside was an additional factor affecting the level of losses in rodents, while its presence in the built-up area increased the mortality of hedgehogs.