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EN
Urbanization affects the ecological and behavioral traits of various species of animals, including birds.We present results concerning long-term fluctuations in breeding densities of nest-box populations of the Blue Tit Cyanistes caeruleus and the Great Tit Parus major in two, structurally and floristically contrasting types of habitat (an urban parkland and a rich deciduous forest) located 10 km apart, in central Poland. This study was conducted in 1999–2012 in the parkland site and in 2002–2012 in the forest site. We found a strong correlation of year-to-year changes in breeding densities of Great Tits between the parkland site and the forest site and a lack of such a correlation in Blue Tits. Breeding densities of Great Tits were much higher in the parkland than in the forest area every year during the study period. Annual changes in breeding densities were not correlated between the species studied. The North Atlantic Oscillation Index (NAO-winter index) tended to influence the density dynamics of the two bird species in the forest area but not in the parkland area.
EN
We examined the variation in the date of the onset of egg laying and clutch size in three peripheral populations of the Afrocanarian Blue Tits Cyanistes teneriffae ultramarinus at the edge of the species and subspecies geographic range. This study was carried out in three study sites, 130–290 km apart, in similar geographic conditions of the South Border Range of the Saharan Atlas in Algeria. Mean altitudes of nesting territories were between 1327 and 1437 m a.s.l. Habitats of the study sites were covered by the secondary, human-modified vegetation, ranging from a maquis shrubland, with the Holm oak Quercus ilex shrubs to woodlands dominated by the Atlas cedar Cedrus atlantica or by the Aleppo pine Pinus halepensis. 169 wooden nest-boxes were monitored for breeding parameters (laying dates and clutch sizes) during the breeding seasons 2007–2009 and 2011–2013. The timing of egg laying was relatively late for the latitude of the study sites, with overall mean laying dates varying between the study sites from 4 to 13 May. The laying date was influenced by the altitude of nesting sites, with the dates being delayed with increasing altitude. Overall mean clutch size differed between the study sites from 5.91 at Djelfa to 8.43 at Aflou. Clutch size tended to decrease with the advance of the breeding season. Because the study populations inhabit areas of similar physical conditions (climate and altitude), the main inter-population source of variation in the breeding parameters studied was probably variation in habitat quality.
EN
Long-term annual variation in the timing of egg laying, clutch size and relationship between clutch size and the progress of the season was analysed for the Pied Flycatcher Ficedula hypoleuca nesting in a mature deciduous woodland in central Poland in 2002-2010. The earliest mean egg laying date was 8 May (2005) and the latest 18 May (2008), resulting in the maximum difference of 10 days between averages for years. No long- term trend was found. The total average of annual mean laying dates was 12 May. For all nine years the average of annual mean clutch sizes was 6.54 [plus or minus] 0.28 (SE) eggs; for individual seasons mean clutch size ranged from 6.0 to 7.1 eggs but differences among years were not significant. Clutch size clearly tended to decline with the progress of the breeding season within years, with some variation between years; correlation for pooled standardized data was -0.49. This supports the idea that in long-distance single-brooded passerine birds clutch size should decrease with the course of the breeding season due to progressively deteriorating food conditions.
4
Content available remote A method for simple assessment of cold sensitivity in insects
EN
A simple index of sensitivity to frost in insects for the general use in ecological studies was introduced. The index is based on a cooling experiment that leads to the estimation of the subzero temperature at which 50% of a sample of particular species life form individuals are killed within 24 hours. By analogy to toxicology, such an estimate was called LTemp[50]. We present the method using our results from a series of simple cooling experiments conducted on larval gooseberry sawflies Nematus ribesii (Scopoli) and imagine queens, workers and males of the hornet Vespa crabro L. LTemp50 indices were -7.2[degrees]C for gooseberry sawfly larvae and ranged from -5.0[degrees]C for male hornets to -9.1[degrees]C for queen hornets. These differences seem to reflect reasonably the specific thermal environment adaptations of the studied insects.
EN
Long-term changes in wetland habitats have been lately reported all over the world. Global warming and, in particular, irrigation and eutrophication of shallow lakes cause changes in vegetation, often in directions differing from the natural ecological succession. As a result, from the viewpoint of waterbirds, their nesting habitats deteriorate, which leads to changes in their breeding biology and distribution. In this paper the nesting of Whiskered Tern Chlidonias hybrida (L.) was studied in changing habitat of Lake Tonga, the El-Kala National Park, NE Algeria in 1996 and 2005.2006. Since the 1960s, there has been a clear trend of extensive development of emergent and floating-leaved vegetation, with up to 80% of the lake surface being currently covered during summer. Nesting colonies of Whiskered Terns are mostly connected with beds of the white water-lily (Nymphaea alba L.). The average distance of breeding colonies from the shore line increased from 176 m in 1966 to 786 m in 2005 and 933 m in 2006. Over the study period, average nest size got twice smaller. Nest diameter was on the average 470 mm in 1996 and 236 mm in 2005.2006. The nests also changed shape and composition. The size and shape of nests were correlated with measures of their composition. Variables characterizing size, shape and composition of nests indeed differed in response to ecological variation of habitat between and within years. Our results suggest that the main function of Whiskered Tern nests is providing a firm support for eggs, incubating adults and young nestlings, which would correspond to the nest support hypothesis of Collias and Collias (1984). Nest size was influenced by ecological conditions in two ways: directly, by changing the availability of construction materials, and indirectly, by changing the distribution of colonies and, thus, physical conditions for nests. We also suggest that some components of the changes in nest size, shape and composition may be linked with the social and sexual signaling system of Whiskered Terns.
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