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We investigated food preferences of three species of dormice, testing consumption by captive animals. One type of food was provided to an animal and its “suitability” scored for each species, according to whether it was or was not consumed. If it was eaten, the time when it was consumed was recorded (after 24, 48 or 72 hours). In total, 17 types of animal food and 46 of plant food were tested. Animal foods offered included different arthropods, eggs, snails and chicken meat. Plant food consisted of fruits, seeds, nuts and green parts. Glis glis consumed – 24% of animal material offered and 100% of plant food types, Dryomys nitedula consumed – 77% of animal and 54% of plant food types. Graphiurus murinus consumed – 94% of animal and 63% of plant food types. G. glis showed a significantly higher preference for plant foods rather than animal material, and preferred plant food much more than the other two species. Both D. nitedula and G. murinus preferred animal more than plant food and did not differ in preferences and diversity of both kinds of food they consumed. Thus, G. glis can be considered as principally a herbivore, while D. nitedula and G. murinus are rather meat-eaters. It can be concluded that food niches, especially of the two European dormice, are separate and thus in natural conditions they do not compete strongly for food resources.
The pattern of autumn migration of the Robin was studied through an analysis of daily dynamics for the birds caught in the years 1984-1997 at four ringing stations (two on the Baltic coast and two in inland Poland). In a given year, migration dynamics was found to be distinctly similar at all stations. It showed conspicuous consistence (± 2 days) in the dates with peak numbers. This could be explained by assuming that Robins take off at the same time across a large breeding ground, and arrive almost simultaneously at stopover sites located over extensive areas. Moreover, migration dynamics from year to year at a given station was also remarkably similar, though this phenomenon was more distinct at the inland stations than at the coastal ones. Day-to-day fluctuations in numbers were on an average the highest at the coastal station most exposed to variable weather, the lowest at the inland stations, and intermediate at the more "sheltered" of the coastal station. The paper discusses the extent to which such results can reflect the influence of weather conditions on passage, or else a precise internal (physiological and genetic) mechanism responsible for the timing of migration.
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