Jenő J. Purger

Coating plasticine eggs can eliminate the overestimation of predation on artificial ground nests

Capsule The use of plasticine eggs coated with a thin layer of rubber instead of entirely plasticine eggs in dummy nests reduced the unnaturally high nest predation rate caused by attracted small mammals, while also enabling the identification of nest predators.

Population Size And Nest Site Selection Of The Spanish Sparrow Passer Hispaniolensis In The Region Of The River Krka (Croatia)

Abstract The breeding range of the Spanish sparrow, Passer hispaniolensis, in Croatia is rapidly expanding. We studied the size of the nesting population and selection of nest site in an area partially included in the Krka National Park. Our results confirm that between 2004 and 2007 in the wider area of the Krka National Park the Spanish sparrow had occupied new localities, and that the number of 160 pairs recorded in 2003 had more than doubled (300–350) by 2007. In the study area, Spanish sparrows nest most commonly in the canopies of introduced planted trees (e.g. Morus alba, Platanus occidentalis, Populus nigra cv. italica). This strategy, with a good access to and diversity of potential nesting sites, enables a further expansion of the species.

Comparative analysis of the diet of feral and house cats and wildcat in Europe

Differences in availability of food resources are often manifested in the differentiation of feeding habits of closely related mammal species. Therefore, we assumed that the diet composition and trophic niche of house (i.e., highly dependent on human households), feral (i.e. independent on human households) domestic cats (Felis silvestris catus) and wildcats (Felis s. silvestris) differs. Based on the literature data from Europe (53 study sites), we compared the diet of these three felids analyzed with use of indirect methods (stomach and scat analyses). In the case of the house cat, we additionally compared consumption data obtained directly from prey brought home. Data were expressed as the relative frequency of occurrence to compare dietary patterns. The main prey of the three cat types were small mammals in different ratios. According to the stomach and scat samples, the diet composition of the cat types showed differences in the consumption of rodents, insectivores, wild ungulates, and household food, supporting the “dietary differences originate from varying resources” hypothesis. More opportunistic house cats had a broader trophic niche than feeding specialist wildcats, while feral cats had an intermediate position. The trophic niche breadth of all three cat types increased along a latitudinal gradient from northern to southern areas of Europe. The predation of the house cat which was examined from prey brought home differed from the data obtained by indirect diet analysis; however, it yielded similar results to the diet of the feral cat and the wildcat. Due to their high numbers and similarity of its diet to the wildcat, house cats are a threat to wild animals; therefore, their predation pressure needs to be further investigated.

The prey composition of the Barn Owl (Tyto alba) with respect to landscape structure of its hunting area (Zala County, Hungary)

Abstract The prey composition of the Barn Owl (Tyto alba) can be monitored indirectly by pellet analysis and we used this method to investigate less known small mammal species of Zala County. The number and abundance of small mammal species depend on the structure of the landscape of Barn Owls’ hunting area, therefore we analysed landscape features in the surrounding circles with 2 km radius around the sampling sites. In 2016 we collected 1106 pellets from 13 sampling localities. From the pellets we identified 21 species of 3022 individuals of small mammals (more than 98% of prey). Among the 21 species there was the rare Parti-colured Bat (Vespertilio murinus) and a new species for the county the Steppe Mouse (Mus spicilegus). Positive correlation was found between the diversity of the small mammal fauna of each sampling site and the landscape complexity (number of the landscape patches) of the Barn Owl hunting area. Relative abundance of the Wood Mouse (Apodemus sylvaticus) showed positive correlation with the number of landscape patches, while the abundance of the Lesser White-toothed Shrew (Crocidura suaveolens), the Miller’s Water Shrew (Neomys anomalus), the Striped Field Mouse (Apodemus agrarius) and the Harvest Mouse (Micromys minutus) was higher in hunting areas with more homogenous landscapes. Significant correlations were found between the relative abundance of some small mammal species and the landscape structure of the potential hunting area of owls that confirmed the consistency in habitat preference of some species. Our results proved that the prey-composition of Barn Owls reflects the land use through the distribution and abundance of small mammal species, therefore this method is suitable for ecological analyses of landscape.

Daily Survival Rates of Eggs in Artificial Ground and Shrub Bird Nests on Small Adriatic Islands

Summary. Predation may cause important losses to the biodiversity of small islands. In this study we analysed the predation pressure on clutches of nesting birds in two islands of the Zadar Archipelago, Olib and Silba, which belong to an Important Bird Area (IBA) in Croatia. We paid special attention to introduced mammals: black rats Rattus rattus and feral domestic cats Felis silvestris catus. In May 2009, we carried out a study with artificial ground and bush nests. One quail egg and a plasticine egg of similar size were placed in each nest. On Olib, the daily survival rate of quail eggs in ground nests (0.92) was similar to that of nests located in shrubs (0.93), whereas on Silba the daily survival rates of quail eggs in ground (0.94) and shrub nests (0.86) were significantly different. We used the marks left on the plasticine eggs to identify nest predators. Many eggs in shrub nests (40% on Olib and 70% on Silba) were predated by hooded crows Corvus cornix. In ground nests on Olib, 43% of eggs were predated by hooded crows and small mammals, mainly black rats. On Silba Island, eggs in 33% of the ground nests were damaged by the above predators and also by the Montpellier snake Malpolon monspessulanus. Contrary to our expectations, feral cats were not found to be egg predators on either of the islands.