National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
The role of UV reflection in parasite egg rejection in reed warbler (Acrocephalus scirpaceus)
Šulc, Michal ; Procházka, Petr (advisor) ; Fuchs, Roman (referee)
One of the best ways how hosts may defend their clutch against brood parasitism is recognition and rejection of parasitic eggs. It has been documented that ability to percept UV light in birds affects their behaviour. By using a spectrophotometer we found that Reed Warbler (Acrocephalus scirpaceus) eggs and Common cuckoo (Cuculus canorus) eggs differ mainly in brightness but also in UV hue. We investigated the influence of birds' UV vision on recognition and rejection of parasitic eggs. Therefore we performed three experiments to reveal the role of eggshell UV reflectance on egg rejection in this host. In the first experiment, we parasitized clutches with artificial white eggs differing only in UV reflectance (UV- and UV+). In the other two, we experimentally reduced UV reflectance from conspecific and host own eggs. We used a UV light blocker, which did not influence the reflectance shape in the other parts of spectra. As a control we used a group of conspecific and own eggs coated in Vaseline, which did not affect eggshell reflectance. In each experiment, we monitored host response to parasitic eggs. Because the Reed Warbler's eggs reflect UV radiation themselves, we expected that white UV- eggs would be rejected as well as the eggs coated in UV blocker at a higher rate than white UV+ eggs and...
Study of selected factors influencing the nesting population of reed warbler (Acrocephalus scirpaceus)
KITTLOVÁ, Lucie
The aim of this work was to study the occurrence, abundance and distribution of breeding population of model species Reed Warbler (Acrocephalus scirpaceus) at selected locations. Subsequent evaluation is based on the monitored nesting parameters: nest height above water surface, water depth, distance of the nest from unvegetated water surface, the distance of the nest from the nearest fixed point, and number of stalks on which the nest was built. Diet spectrum was also detected. The results were statistically analysed in order to find out if and how these factors could influence nesting success and density of Reed Warbler population. Marginal influence on nesting success was found out only in these parameters: the number of stalks (the nests with three stalks was the most successful) and the distance from the fixed point. Successful nests were about 26% further (1.8 m) than the unsuccessful nests that could be explained by the predator factor. The most numerous insect orders in selected locations were Diptera (60%), Hymenoptera (21%) and Araneae (12%).

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