Predation of common wall lizards: experiences from a study using scentless plasticine lizards

The potential influence of predators on lacertid lizards has been studied by using models made of plasticine which shows the attack marks of predators and as such allows their identification and estimation of predation pressure. The general aim was to study predation on plasticine models of lizards and to improve methods, since the results depend on the number of plasticine models used, their spatial pattern and the duration of experiments. We estimated the density of the common wall lizard Podarcis muralis population on stone walls of a vineyard in the city of Pécs (Hungary) in August 2015 in order to imitate the real density in our experiment with plasticine models. The density of common wall lizards was 8.2 ind. /100 m2 and accordingly we placed 25 scentless plasticine lizards on the stone walls on the first transect with 10 m distance between them, which imitates the real pattern. In the second transect 25 lizard models were placed more sparsely, the distance between them being 20 m. During four weeks the predation rate was 24% in densely spaced plasticine lizards and 40% in sparsely spaced plasticine lizards, but the difference was not significant. The daily survival rate of densely spaced lizards was 0.99 (=99.1%) and that of sparsely spaced lizard models was 0.98 (=98.25%), but this difference was not significant either. On the basis of marks left on plasticine lizards, mammal predators (e.g. beech marten) dominated, while the impact of bird predators was smaller than expected. Predators attacked the head of plasticine lizards more frequently than their trunk, tail or limbs, but a significant preference of body parts was not detected. From our experience it is important to study the distribution and density of real animals, to imitate their real pattern, instead of an arbitrarily designed experiment with models. The typical scent of plasticine also could influence the results, which can be avoided by using scentless plasticine models coated with liquid rubber. We suggest the calculation of daily survival rates in order to produce results that allow the comparison of different studies

Predation of common wall lizards: experiences from a study using scentless plasticine lizards

The potential influence of predators on lacertid lizards has been studied by using models made of plasticine which shows the attack marks of predators and as such allows their identification and estimation of predation pressure. The general aim was to study predation on plasticine models of lizards and to improve methods, since the results depend on the number of plasticine models used, their spatial pattern and the duration of experiments. We estimated the density of the common wall lizard Podarcis muralis population on stone walls of a vineyard in the city of Pécs (Hungary) in August 2015 in order to imitate the real density in our experiment with plasticine models. The density of common wall lizards was 8.2 ind. /100 m2 and accordingly we placed 25 scentless plasticine lizards on the stone walls on the first transect with 10 m distance between them, which imitates the real pattern. In the second transect 25 lizard models were placed more sparsely, the distance between them being 20 m. During four weeks the predation rate was 24% in densely spaced plasticine lizards and 40% in sparsely spaced plasticine lizards, but the difference was not significant. The daily survival rate of densely spaced lizards was 0.99 (=99.1%) and that of sparsely spaced lizard models was 0.98 (=98.25%), but this difference was not significant either. On the basis of marks left on plasticine lizards, mammal predators (e.g. beech marten) dominated, while the impact of bird predators was smaller than expected. Predators attacked the head of plasticine lizards more frequently than their trunk, tail or limbs, but a significant preference of body parts was not detected. From our experience it is important to study the distribution and density of real animals, to imitate their real pattern, instead of an arbitrarily designed experiment with models. The typical scent of plasticine also could influence the results, which can be avoided by using scentless plasticine models coated with liquid rubber. We suggest the calculation of daily survival rates in order to produce results that allow the comparison of different studies

Connection between prey composition and the landscape structure in the hunting area of Barn Owl’s (Tyto alba) in Baranja (Croatia)

Background and purpose: The assumption that the species composition and the relative abundance of small mammals in pellets of Barn Owls reflects the landscape structure of the hunting area is tested, based on habitat preferences of small mammals identified from pellets collected in the hilly and lowland parts of Baranja county (Croatia). Materials and methods: During 2007 we collected 2395 whole pellets and their fragments in 21 localities, from which 6613 prey remains were identified as belonging to small mammals (99.5%) of 23 species. The correlation between the relative abundance of mammal species and landscape structures (habitat types and landscape features) was tested. Results: There was a significant correlation between the relative abundance of seven small mammal species and the proportion of particular landscape structure classes. The number of small mammal species showed a negative correlation with the area of inland marshes. The evenness of the small mammal fauna grew with the mosaicity of landscape and the length of the borders in the owl’s hunting area. In the total prey the Common Vole (Microtus arvalis) dominated with more than 62%, which indicates its population outbreak. The diversity and evenness of small mammals in the hilly and lowland regions did not differ. Conclusions: We found significant correlations between the relative abundance of some small mammal species and the landscape structure classes in the owls’ hunting area. Our results suggested that the diversity of small mammals increases as the mosaic of the landscape increases, while the degree of population outbreak of the Common Vole decreases. These relationships should be taken into consideration when designing landscapes or changing land use.</p

Óhid és Kisgörbő környékének (Zala megye) kisemlős faunája gyöngybagoly (Tyto alba) köpetek vizsgálata alapján | [Small mammal fauna of the surroundings of Óhíd and Kisgörbő (Zala County, Hungary), based on barn owl (Tyto alba) pellet analysis]

Barn owl pellets were collected in Somogy county in 2011, between Sümeg and Zalaszentgrót (investigated area: XN60 quadrate of 10 × 10 km UTM grid). From a total of 290 whole pellets and their fragments, 1400 prey remnants were identified. The analysis of pellets showed that the prey of barn owl in the study area consisted of mammals (98.8%), birds (0.6%), beetles (0.4%) and amphibians (0.2%). Mammal prey consisted of Soricidae 46.9% (Crocidura leucodon, C. suaveolens, Sorex araneus, S. minutus, Neomys anomalus, Neomys fodiens) Vespertilionidae 0.2% (Plecotus austriacus), Gliridae 0.3% (Muscardinus avellanarius), Cricetidae 29% (Microtus agrestis, M. arvalis, M. subterraneus, Arvicola amphibius, Myodes glareolus) and Muridae 23.6% (Apodemus agrarius, A. flavicollis, A. sylvaticus, Micromys minutus, Mus musculus, Rattus norvegicus). The occurrence of 18 small mammal species had been known in the investigated area before our survey. This study did not confirm the occurrence of common mole (Talpa europaea) and Weasel (Mustella nivalis), although common dormouse (Muscardinus avellanarius), wood mouse (Apodemus sylvaticus) and brown rat (Rattus norvegicus) were detected. According to our knowledge 21 small mammal species live in the study area

Does human hair attract or deter potential ground nest predators?

The nests of rare and threatened bird and reptile species that breed on the ground are often attempted to be protected from predators with fences, grids, and various repellent materials. Results of some experiments refer to the repellent function of human scent, whereas others suggest that it has an attractive role. We aimed to investigate how effectively ground nests can be protected from predators if human hair is placed around nests. We performed the experiment in a riverine oak-elm-ash forest using 90 artificial nests, each with 1 quail and 1 plasticine egg: 30 nests were protected with a game fence, 30 nests were surrounded with human hair and 30 nests were unprotected (control). During the 24 days, predators damaged 23% of the nests protected by a game fence, 40% of unprotected nests and 47% of the nests surrounded with hair. The daily survival rate of quail eggs in nests protected with a game fence was significantly higher than the ones in the nests surrounded with human hair. Only 18% of the quail eggs and 36% of plasticine eggs were damaged. Such difference can be explained by the fact that small-bodied birds and mammals could pass through the game fence and left traces on plasticine eggs but they were unable to crack the shell of quail eggs. Within the game fence, denser vegetation can provide better nesting conditions and result in greater breeding success. The repellent role of human hair has not been proved, on the contrary, in some cases we have observed signs of its attractant role, such as small-bodied birds took hair away for nest building

Investigating the relationship between the prey composition of Barn Owls (Tyto alba) and the habitat structure of their hunting range in the Marcal Basin (Hungary), based on pellet analysis

Little was known about the small mammal fauna of the Marcal Basin to date, therefore we collected 1,144 Barn Owl pellets from 15 locations in 2017. After the analysis of the pellets, remnants of 3,063 prey items were identified, of which 97.5% were small mammals, belonging to 21 species, while the remaining 2.5% were birds, frogs and insects. Mammal prey items consisted of Cricetidae 41%, Muridae 31% and Soricidae 28%, and in some samples, we found the remnants of European Mole (Talpa europaea), Kuhl’s Pipistrelle (Pipistrellus kuhlii), Hazel Dormouse (Muscardinus avellanarius) and Least Weasel (Mustela nivalis). Small mammal species were classified into four functional groups based on their preferences for urban, open, forest or wetland habitats. We investigated whether their relative abundances match with the proportions of the four habitat types in the assumed Barn Owl hunting ranges (cca. 2 km radius circle) in five sample sites. The relative abundance of small mammal species preferring urban habitats showed concordance with the proportion of the appropriate habitat types in the hunting area in two samples, while such concordance was proved for species favouring open, forest and wetland habitats just in one out of five samples. Small mammal functional groups represented in the prey composition do not directly correspond to the proportion of their typical habitats. We conclude that the abundance of various prey types is not suitable for characterising the landscape within the Barn Owl’s hunting range

European Hamster at the edge: declining in nature and rare in owl pellets×

Over the last decades, the European Hamster (Cricetus cricetus) has been declining in many parts of its European range. Due to the lack of recent information on the occurrence and status of the European Hamster in the south-western Carpathian Basin west of the Danube, we used information gathered from prey remains in Common Barn-owl (Tyto alba) pellets. In spite of considerable sampling effort, we retrieved only few hamster remnants. Two skulls were found in Podolje (Croatia) in 2007 and 2016, respectively. Further five hamsters were retrieved from pellets collected in 2017, 11 km to the northwest in Udvar (Hungary). In Sátorhely, 5 km north from Udvar, one roadkill male was found on 27.07.2019. Testimonies from local inhabitants confirmed the current presence of the European Hamster in the area. Our results suggest the presence of a small isolated population in the border area of Croatia (UTM 10 km grid square CR27) and Hungary (CR18, CR19). This small isolated population is on the south-western limit of the range of the species. We presume that the population requires conservation attention because of its isolated position at the edge of the species’ range, its small size and low abundance. We call for a transboundary action by nature conservation authorities in Croatia and Hungary