Control of the numbers of voles - Microtus arvalis (Pall.) by a group of predatory birds andmammals ; Control of the numbers of voles - Microtus arvalis (Pall.) by a group of predatory birds and mammals
The article is based on studies either already published or prepared for printing on the relations between predatory birds and mammals and the common vole. The functional reactions of predators to variations in density of voles are discussed (Fig. 1). The group of species highly specialized in catching this vole and the group of species with diets of a polyphagous character have been distinguished within the community of predators examined. It is emphasised that penetration for hunting purposes of different crops is conditioned by the vole’s density (Tab. I). Numerical increase in predators depends on the biology of the species and may be the effect of migration (to a considerable distance in the case of buzzards or short expeditions in the case of cats) or natality (Fig. 2).Using estimates of the extent of pressure by predators on vole populations as a basis, the author states that the predatory birds and mammals examined are not capable of counteracting mass irruptions of the vole neither are they responsible for reducing such mass irruption (see Fig. 3). Mass appearance of the vole coincides with the period of particularly luxuriant development of vegetation, which makes it far more difficult for the predators to catch the rodents. Therefore despite the lack of accuracy in estimates of pressure it would appear that the controlling role of predators cannot be considered as equivalent to the possibility of counteracting mass appearances of the vole. It may be that the high degree of pressure by predators on voles when densities are low increases the length of the cycle and reduces the threshold numbers of the future irruption. Further studies are necessary to solve this problem. It is suggested that the mosaic character of the area should be intensified (e.g. alternating crops preferred by voles with cultivated fields of root crops) which wTould make contact between voles more difficult and facilitate their capture by predators. Emphasis has also been laid on the question of unjustified shooting by hunters and gamekeepers of certain predators (e.g. cats).
Program Operacyjny Polska Cyfrowa, lata 2014-2020, Działanie 2.3 : Cyfrowa dostępność i użyteczność sektora publicznego; środki z Europejskiego Funduszu Rozwoju Regionalnego oraz współfinansowania krajowego z budżetu państwa
Dehnel, August Gustaw (1903–1962)
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