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1

Within-clutch variation in egg dimensions of Loggerhead Shrike [Lanius ludovicianus] in South-Central Florida

100%
Yosef R., Zduniak P.
Biological Letters
|
2004
|
tom 41
|
nr 2
155-162
2

Colour variation in the common hamster Cricetus cricetus in the north-eastern foot-hills of the Harz Mountains

100%
Kayser A., Stubbe M.
Acta Theriologica
|
2000
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tom 45
|
nr 3
We investigated the occurrence of colour variations in the common hamster Cricetus cricetus (Linnaeus, 1758) between 1915 and 1980 in the north-eastern foot-hills of the Harz Mountains in Saxony-Anhalt. Material was collected by a professional hamster trapper. The most frequent colour variants were white hamsters followed by piebald and yellow animals. The occurrence of colour morphs was strongly male biased. Only one black hamster, probably an atypical melanistic form, was found in the entire sample of 73 657 hamsters. Overall the percentage of variant individuals was 0.0855%. The frequency decreased significantly over the observed period. Investigations during the 1990s in a neighbouring area showed no colour variation in a smaller sample set. A possible connection between the decline in hamster numbers during this period in the study area and the reduced frequency of colour morphs is discussed.
3

Population decline of the Little Owl [Athene noctua Scop.] in the Chech Republic

84%
Salek M., Schropfer L.
Polish Journal of Ecology
|
2008
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tom 56
|
nr 3
527-534
A change of land use is often cited as a causal factor in the decline of many species of farmland birds. Populations of the Little Owl (Athene noctua Scop., 1769) have notably decreased throughout Europe in the last 60 years, including the Czech Republic. The aims of this study were to estimate the recent population trend of the Little Owl and to analyze the importance of altitude and grassland habitat within Little Owl territories. The population trend of the Little Owl in the Czech Republic has still decreasing tendency. The population density dropped from 0.33 breeding pairs (bps) 10 km⁻² to 0.12 bps 10 km⁻² in the first (1993–1995) and second (1998–1999) monitoring program, respectively. The decline is apparent also from results from last Little Owl monitoring program which were carried out in 2005–2006 on 35 study plots (4607 km²). The average population density was estimated at 0.1 bps 10 km⁻². A distinct feature of these recent populations is that they occur in the places with relatively high local density (core areas) in comparison to the surroundings, which are unoccupied. At present, the Little Owl rarely breeds in natural tree cavities, but rather the majority of nesting sites are situated in human artifacts, especially within agricultural objects. Areas in which the Little Owl occurs have a significantly larger proportion of grasslands and are situated at lower altitudes. We suggest that the changes in agricultural landscape associated with disappearance of traditional farming management of grassland habitats, forceful pasturage and regular mowing were the main factors in this long-term population decline. The recent decrease of Little Owls could be also the consequence of the existence of small isolated populations in which mortality is not balanced by immigration from surrounding areas.
4
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A piliminary survey of House Sparrow (Passer domesticus) in Ramakrishna Beach Road, Vishakhapatnam (Vizag), Andhra Pradesh

84%
Laxmi Narayana B., Vasudeva Rao V., Sandeep M., Surender G., Ramaligeswara Rao A. V. L. N.
International Letters of Natural Sciences
|
2015
|
tom 04
We studied the population records of House Sparrow Passer domesticus 16th to 20th December 2011 during winter in Ramakrishna Beach Road Vishakhapatnam town, Andhra Pradesh. The ecological density of House Sparrow was investigated using fixed width transects. A total of 189 House sparrows were recorded. The present study shows that a notable population of House Sparrow in Beach Road.
5

Different extinction risks of the breeding colonies of Rooks Corvus frugilegus in rural and urban areas of SW Poland

67%
Orlowski G., Czapulak A.
Acta Ornithologica
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2007
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tom 42
|
nr 2
145-155
6

Czynniki kształtujące procesy depopolacyjne na obszarach wiejskich Polski północnej

67%
Gwiazdzinska-Goraj M.
Acta Scientiarum Polonorum. Administratio Locorum
|
2018
|
tom 17
|
nr 4
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