Fragments of idle fields in urbanized zones may attract threatened bird species to nest, but, at the same time, may be favoured by generalist nest predators attracted by food resources abundant in urban areas. Only few studies have analysed effects of nest predation risk in suburban habitat fragments while considering the character of the surrounding landscape. We used artificial nests to examine possible effects of patch size and edge distance, extent of surrounding urbanization, habitat composition and heterogeneity on nest predation risk to ground-nesting birds in idle fields within suburban areas. Nest predation risk varied regardless of patch size. Edge effect appeared only combined with the proportion of particular habitat types in the surrounding landscape. Character of surrounding landscape was strongly influential. In particular, predation risk was positively correlated with proportions of unstable disturbed sites nearby but negatively
correlated with proportions of adjacent meadows and forests. From the standpoint of nature conservation and effective support to bird diversity in suburban areas, we highlight the importance of diverse nature-like stands such as meadows or forest fragments.
In large parts of Europe Pardosa spp. (Lycosidae) are among the most abundant wolf spiders in arable fields and potentially important natural control agents of pests. We studied the influence of landscape factors on activity density, adult body size and fecundity of P. agrestis in 29 winter oilseed rape fields (Brassica napus L.) in Eastern Austria using pitfall traps. Landscape data were obtained for eight circular landscape sections around each field (radii 250-2000 m). Multivariate regression models were used to analyze the data. Activity density was highest when the length of strips of grassy road-sides in the surroundings was highest and distance to the next grassy fallow lowest. Body size was negatively related to activity density and to the length of road-side strips and positively to woody areas in the vicinity of the fields. Clutch size was unrelated to any of the landscape factors tested but was positively correlated with female body size. Woody areas and grassy fallow in the close vicinity of the fields had a positive influence on number of offspring per female and total number of offspring. These results indicate that various non-crop components in the landscape surrounding oilseed rape fields can specifically influence the activity density and fitness-related traits of P. agrestis in crops. The possible role of Pardosa spp. in natural pest control is discussed. and Thomas Drapela, Thomas Frank, Xaver Heer, Dietmar Moser, Johann G. Zaller.