Piscivorous birds are often blamed for causing significant damage to fish stocks. Various methods are used to determine the composition of their food, each of them has limits in its ability to determine the complete food spectrum. This work maps the complete food composition of 14 species of fish-eating birds with a method that is not commonly used. Method used in this work uses analysis of publicly available photos on Google.com. In addition to the complete composition of the food, the species composition of the non-fish part of the prey was also determined, and in the case of the Great Cormorant (Phalacrocorax carbo), also the length of the fishes it catches. The aim of this work is to reveal the usability of this method for these purposes. A total of 2350 retrieved photographs were analyzed. The results obtained by photo analysis are in all cases compared with data in the available literature. For representatives of heron birds (Ardeidae), the analysis of photographs provided good information on the food spectrum of individual birds and on the qualitative composition of the non-fish component. It also provided relatively good information on the diet of the White-tailed Eagle (Haliaeetus albicilla), but the bird part of the prey was slightly underestimated. In the diet of the Great Crested Grebe...
| Identifer | oai:union.ndltd.org:nusl.cz/oai:invenio.nusl.cz:437639 |
| Date | January 2021 |
| Creators | Mach, Jakub |
| Contributors | Čech, Martin, Vejřík, Lukáš |
| Source Sets | Czech ETDs |
| Language | Czech |
| Detected Language | English |
| Type | info:eu-repo/semantics/masterThesis |
| Rights | info:eu-repo/semantics/restrictedAccess |
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