Temporal changes in proportions of small mammals in the diet of the mammalian and avian predators in Slovakia

Abstract

The paper presents a brief account of the temporal changes found in proportions of the mammal components in the diets of several species of predators (owls and carnivores) collected from various sites in Slovakia and originating in various periods (Late Pleistocene–Recent). The material collected from the Šarkanica Cave (Muráňska planina Mts.) contained bones in three layers, dated using the radiocarbon analysis (14C) to 18,000–21,000 years BP (18–21 Ka), showing relatively small differences in composition of the fossil diet of Bubo scandiacus with predominance of Lasiopodomys gregalis (73.3%) and Chionomys nivalis (6.9%). A similar type of material from the Nový 3 Cave (Belianske Tatry Mts.), dated to the period of 30 Ka, contained more numerous remnants of Lemmus cf. lemmus and Sorex tundrensis. Undated samples from the Nový 1 Cave and from the Šarkania diera Cave (Súľovské skaly Mts.), which differ in their higher abundance of Dicrostonyx cf. gulielmi, are probably dated from the colder period of the last glacial maximum. Three samples from caves in the Veľká Fatra Mts. dated from the Late Pleistocene (Upper Dryas) originated from carnivores, with differences in relative proportions of predominant prey species: Chionomys nivalis (80.0%) and Lasiopodomys gregalis (14.3%), while remains of Cricetus cricetus (0.6%) also appear there. Two examples of differences in the diet composition of Strix aluco in the Veľká Fatra Mts. are present in samples dated to the Holocene period: natural development of forest fauna in the environs of Dolný Harmanec and anthropogenic influence in the form of three deforestation periods in the Tlstá massif near Blatnica (both Veľká Fatra Mts.). A sample set of the diet of Tyto alba dated >500 years BP from a church in Žilina is compared with a recent sample set of this owl diet from the Turčianska kotlina Basin and from the Danubian Lowland (Tekovské Lužany). The main difference lies in the greater proportion of the murid rodents and the relatively lower abundance of Microtus arvalis in the sample from the 16th century. Similar results were found comparing samples of Tyto alba diet, taken from a cave near Hatiny (Slovenský kras Mts.) and expected to be 100 years old, with more recent samples from the Košická kotlina Basin. The collection from the Hatiny Cave differs from the recent material in the presence of Sicista trizona and Alexandromys oeconomus. The recent samples of the diet of Bubo bubo taken from the Horné Považie Basin differ from the samples dated back more than 70 years ago by a high proportion of the genus Apodemus and a predominant incidence of frogs, while the old samples come from the period of the communist influence of the agricultural production causing serious environmental changes in the countryside (1950s) and as a result, a greater volume of large prey species, Rattus norvegicus, Arvicola amphibius, Lepus europaeus, and Erinaceus roumanicus. Since 1990, the availability of large prey for Bubo bubo has decreased due to the decline of livestock farming and a consequent successional overgrowing of pasture land by trees.