Věstonická resivoir Nature Reserve (South Moravia)
The main aim of the survey was to identify those species which prey on the nests of ground of nesting birds, especially in bird colonies on the islands. These predators may have a significant effect on the population of nesting birds in the colonies especially if:
- There is a stable population of mammalian predators on the islands and
- They are able to predate on nests during the nesting period
From October - November 2009, the monitoring of select mammal species at Věstonická Reservoir Nature Reserve took place, with a possible impact on the populations of nesting birds. Monitoring was carried out on 18 monitoring rafts and via seven camera traps, and as a supplementary method, the monitoring of residence signs and random observations also took place. Four species carnivorous mammals were found: Eurasian otter (Lutra lutra), Beech marten (Martes foina), European polecat (Mustela putorius) and Northern raccoon (Procyon lotor). As the Eurasian otter is specialised in fishing, its potential impact on the bird population is minimal. In contrast, the European polecat, the Northern raccoon and the Marten are species in which the waterfowl can form an important component of their diet. Therefore, they can significantly affect the success of nesting bird colonies. The colonies are located on relatively isolated and small islands, predation is unlikely to occur. The exception, however, is Kostelní Ostrov, where the marten is permanently living. If this island is re-populated with colonies of birds, the marten can have a major impact on the success of nesting on the island. Other species found in the Czech Republic that put water bird nests on islands at risk are the American mink (Neovison vison) and the Brown rat (Rattus norvegicus). The survey did not find either however. As both species are very effectively captured by the monitoring rafts, it is likely they are not permanently present here.