A study was made of the influence of trampling by grazing animals on the nesting success of real nests (meadow pipit, Anthus pratensis; water pipit, Anthus spinoletta; and skylark, Alauda arvensis) and simulated nests (caps from jam-jars filled by green plasticine) on pasture in the Orlické Mountains and on unmanaged alpine meadows in the Jeseníky Mountains (Czech Republic, Central Europe). While the pasture was continuously grazed by livestock at high densities, unmanaged alpine meadow was grazed only by wild large herbivores at far lower densities. Trampling was the primary cause of nest failure in the Orlické Mountains, but was infrequent in the Jeseníky Mountains. The number of real nests lost by trampling corresponded to simulated nests within the localities. Spatial distribution of simulated nests had no effect on their survival on intensively grazed fields. The results indicate that grazing animals negatively influenced the nesting success of real and simulated nests of grassland passerines on continuously grazed mountain pasture. The use of simulated nests was an adequate method of predicting trampling losses by natural nests.
Slavík modráček (Luscinia svecica) je drobný drozdovitý pěvec obývající v 10 poddruzích rozsáhlý areál od Evropy až po Aljašku. V České republice se vyskytují poddruhy dva – modráček středoevropský (L. s. cyanecula), původně považovaný jen za protahující a jehož hnízdění v ČR bylo potvrzeno až v druhé polovině 20. stol., a modráček tundrový (L. s. svecica) objevený v Krkonoších až v r. 1977. Článek přibližuje rozdíly ve zbarvení, rozšíření a hnízdní biologii. and The Bluethroat (Luscinia svecica) is a small turdid passerine with ten subspecies inhabiting a huge distribution range extending from Europe to Alaska. In the Czech Republic, two subspecies occur – the White-spotted Bluethroat (L. s. cyanecula), originally considered to be migrating there only (its nesting was not confirmed in the Czech Republic until the second half of the 20th century), and the Red-spotted Bluethroat (L. s. svecica) found in the Krkonoše Mountains as late as 1977.
We tested the hypothesis that males of meadow pipits (Anthus pratensis) respond differentially to simulated territorial intrusions (song playback + bird model) by conspecific, related (tree pipit, Anthus trivialis), and unrelated individuals (willow warbler, Phylloscopus trochilus), and evaluated the effect of playback order. All tested males responded aggressively to the conspecific playback; reactions to heterospecific stimuli occurred only after previous excitation by the conspecific song and dummy, and were usually weaker. Apparently, although males were able to discriminate between playbacks, excitation by intrusion of a conspecific rival elicited an aggressive reaction to otherwise neutral stimuli. Reactions to heterospecific playbacks closely following the conspecific one did not differ significantly between congeneric and unrelated species. The response to a subsequent heterospecific stimulus, however, was taxon-dependent: congeneric species elicited a significantly stronger reaction than an unrelated one. We presume that this was due to the morphological similarity between pipits, and that the more intensive reaction could have been caused by stronger visual stimulus from the respective model. We discuss the potential benefits as well as limitations of using models (dummies) in playback experiments, and suggest that overexcitation by previous stimuli should be considered during experimental setup and data analysis in studies focusing both on interspecific aggressiveness and on neighbour-stranger interactions.