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Documents disponibles écrits par cet auteur (23)
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Article
Xenia Schlindwein, Auteur ; Christoph Randler, Auteur ; Nadine Kalb, Auteur ; Jan Dvorak, Auteur ; Thomas K. Gottschalk, AuteurCamera traps are increasingly used to estimate the density of animals as well as their activity patterns. As camera traps allow monitoring of animals over long periods of time without disturbance, they are especially useful to observe changes in[...]
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Christoph Randler, AuteurDuring their staging at stopover sites, migrants may compete with resident species over food resources ("resource competition hypothesis"), or migrants feed on surplus that is not utilised by the residents. Here, I studied foraging behaviour of [...]
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Marc I. Foerschler, Auteur ; Christoph Randler, Auteur ; Jochen Dierschke, Auteur ; Franz Bairlein, AuteurCapsule We found closely related Cyprus Wheatears Oenanthe cypriaca and Pied Wheatears Oenanthe pleschanka to differ significantly from each other in 14 external morphometric characters, supporting the independent taxonomic status of both forms.[...]
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Christoph Randler, AuteurThe foraging behaviour of the passage migrant Spotted Flycatcher, Muscicapa striata (Pallas, 1764), was compared with the breeding migrant Cyprus Wheatear, Oenanthe cypriaca (Homeyer, 1884), in Cyprus during May 2009. M. striata preferred higher[...]
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Marc I. Foerschler, Auteur ; Christoph Randler, AuteurWe studied the song of the insular Cyprus Short-toed Treecreeper, Certhia brachydactyla dorotheae Hartert, 1904, and compared it with the songs of mainland populations. The song of dorotheae differs from the Central European and south-west Europ[...]
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Christoph Randler, AuteurAnimals usually flee from an approaching human because humans are perceived as potential predators and animals respond accordingly. The distance at which this reaction occurs is termed 'flight initiation distance? (FID). Variation in FID represe[...]
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Christoph Randler, AuteurMating patterns in hybrid zones may be important for maintaining a stable hybrid zone. Theory suggests that hybrid zones are stable due to assortative mating outside the zone. To test whether assortative mating occurs in the crow hybrid zone in [...]
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Christoph Randler, AuteurThe two hybrids spent more time feeding and less time resting and in agonistic interaction than the parent species. Comfort behavior equaled that of mallard. None of the hybrids showed courtship behavior. In feeding, the hybrids spent more time [...]
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Christoph Randler, AuteurHybridization and speciation are central to evolutionary biology. Although birds have been studied more thoroughly than any other vertebrate class, there have still been few macro-evolutionary analyses. Here, I present results based on 65 phylog[...]
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In 1999 Middle Spotted Woodpeckers have been censused at the 'Stromberg', about 40 km north of Stuttgart. The study area covers 122 square kilometres and comprises 7920 ha of woodland, with a high percentage of oak trees. 19 random sample plots [...]
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Christoph Randler, Auteur ; Constanze Teichmann, Auteur ; Stefan Pentzold, AuteurNiche partitioning has been examined in breeding bird communities and in winter quarters, but has received less attention when comparing a resident breeder and migrants during spring. Here, such an assemblage of species of the same genus (Oenant[...]
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Christoph Randler, AuteurPopulation trend of urban Mallards and changes in the proportion of hybrids were studied in and around Stuttgart (9degree10'/48degree47'), SW-Germany, to assess the potential threats posed by hybridisation with other waterfowl to the indigenous [...]
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Christoph Randler, AuteurPopulation trend of urban Mallards and changes in the proportion of hybrids were studied in and around Stuttgart (9degree10\'/48degree47\'), SW-Germany, to assess the potential threats posed by hybridisation with other waterfowl to the indigenou[...]
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Christoph Randler, AuteurApparent hybrids between Common Pochard and Tufted Duck have been noted in west-central Europe in the wild since 1934. This analysis is based on 467 observations of 501 such hybrids in Germany, Austria and Switzerland. 94 % of all observations a[...]
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The german population comprises 20% of the Middle Spotted Woodpecker's world population. Therefore monitoring and conservation is urgently needed. Here, I present the development of a small population in an isolated area, the Favoritepark in Lud[...]
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Christoph Randler, AuteurHybrid zones provide a unique opportunity to study the dynamics of isolation barriers. Pre-zygotic isolation through assortative or conspecific mating is thought to be an important aspect of reinforcement and speciation. Although assortative mat[...]
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Christoph Randler, AuteurPresumed wild hybrids between the Common Pochard (Aythya ferina) and the Ferruginous Duck (A. nyroca) have been noted in Central Europe first in 1955. Hybridization between these two species is very common and their offspring is said to be ferti[...]
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Marion Weisser, Auteur ; Christoph Randler, AuteurBrood rearing behaviour of feral Greylag Geese (Anser anser) was observed at Max-Eyth-See in Stuttgart, Germany, during the breeding season of 2004 by M. Weisser. We aimed at testing three hypotheses: 1) division of labour between males and fema[...]
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Christoph Randler, Auteur ; Marc I. Foerschler, Auteur ; Javier Gonzalez, Auteur ; Mansour Aliabadian, Auteur ; Franz Bairlein, Auteur ; Michael Wink, AuteurThe insular endemic Cyprus Wheatear Oenanthe cypriaca has been considered as a subspecies of Pied Wheatear O. pleschanka. However, due to several differences in behaviour, habitat selection and morphology, it is currently treated by most authors[...]
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Vigilance (scan rate) should correlate positively with the distance to a refuge ("protective cover"). Vigilance and distance to water were observed in Eurasian Coots Fulica atra feeding onshore. The aim of the study was to examine the relationsh[...]
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Cormorants Phalacrocorax carbo sinensis are regularly counted at their roost Pleidelsheimer Baggersee 20 km north of Stuttgart/SW-Germany at least three times per month. There is a continuing steady increase in numbers in contradiction to the nu[...]
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An observation of a diurnal migrating Treecreeper Certhia familiaris is described. The bird moved in southerly direction along a river's channel. Sometimes it sang a short sequence, which was more quiet ("subsong") than its normal song.
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Christoph Randler, AuteurDuring both feeding and preening, coots Fulica atra regularly interrupt their activities to visually scan their environment. This behaviour is considered to be used for detecting predators. Animals in groups lower their individual vigilance sinc[...]
