The species composition and relative density of bats were compared in forests of various sizes occurring as “islands” in the agricultural landscape of central Poland. The following island categories were distinguished: very small (0.3–0.7 km2), small (1.0–1.5 km2), medium (2.0–3.5km2) and large (approx. 18 km2). Bats flying over lanes were caught at 34 mist net stations in 13 islands at the end of June and beginning of July (period I) and again at the end of July and beginning of August (period II). Twelve species of bats were recorded (Plecotus auritus, Eptesicus serotinus and Barbastella barbastellus were the dominant species), and the number of species in specific categories of islands ranged from 8–9, except in the very small islands, where only 4 species were confirmed. Species diversity rose with the size of the islands. Nyctalus leisleri and Myotis mystacinus were caught only in the large island. The frequency of B. barbastellus and Nyctalus noctula clearly increased with island size as opposed to E. serotinus and P. auritus. The relative density (mean numbers of individuals caught at one location on one night) during period I increased with island size from very small (1.8) to large (8.1), while during period II, the highest values were achieved in the medium-sized islands (13.4). The mean number of species for one location and night rose in a similar manner. Forest fragmentation to very small units of less than 1 km2 in size negatively influences bat ensembles.
Variation in nest survival rates is often ascribed to differences in predator communities. Because corvids are the dominant nest predators in many landscapes with fragmented woodland, their absence may have effect on both the overall nest success and its relationship to habitat features. Nest success of Sylvia atricapilla was examined in two habitats in agricultural landscape of SW Slovakia, where corvids were rare/absent. The daily nest survival rate (126 nests) was 0.977 (95% CI: 0.966–0.984) and 0.966 (0.948–0.977) for the egg and nestling stage, respectively, yielding a nest success of 0.52 (0.37–0.64) over a 24-day period. These values are higher than in comparable studies from central Europe, although predation was still the leading cause of nesting failure (more or equal to 71% of 48 failed nests). Correlational evidence suggests link between local absence of corvids and the relatively high nest survival, which was only weakly affected by nest site and habitat characteristics. Nest survival was not detectably higher in forest fragment than in windbreaks and did not increase with distance from forest-field edge or with vegetation concealment. We conclude that both the habitat features and composition of local predator community should be considered when explaining patterns in nest survival rate.
Parameters of breeding were studied in seven rookeries in the agricultural landscape of eastern Poland. Within foraging territories near colonies, proportions of environmental components were defined, and avoided and preferred types of crops were distinguished. The mean clutch size, mean number of hatchlings and mean number of fledglings per successful brood did not differ between colonies and did not depend on colony size. In contrast, total losses at the stage of egg incubation and feeding chicks, the mean number of fledglings calculated per breeding pair and the overall breeding success were different. Foraging territories around each colony usually had different proportions of preferred and avoided crops. Breeding success depended positively on the area of preferred crops: spring cereals and meadows and pastures. Breeding success seemed to decrease with the area covered by avoided crops and winter crops, but the relationship was not significant. The area of spring cereals was positively but not significantly correlated with the mean number of fledglings.
Habitat preferences of nine adult raccoon dogs were investigated during different seasons using compositional analysis after
Aebischer et al. (1993). The study area (33 km²) with its mosaic landscape of forest and farmland was located in Southern Brandenburg
in eastern Germany (13°56′ E, 51°37' N). For analysis eight habitat categories were distinguished. Grassland and coniferous woods
were favoured both within 95 % fixed-kernel (K95) and within core areas (K50). Grassland offered food at most times of the year and particularly after harvesting of fields. Abandoned badger dens located in coniferous woods within K50 were used by raccoon dogs all year round whereas they apparently avoided anthropogenic structures. Other habitat categories were used randomly and we detected no seasonal differences in relative usage. Such heterogeneous agricultural landscapes dominate the central and western European landscape. Furthermore, short winters and low density of top predators provide beneficial living conditions for raccoon dogs. Its
flexibility in habitat use, omnivorous diet and ability to disperse over long distances facilitate a further expansion of the raccoon dog in
western and southern Europe.
A three-year experimental study with artificial ground nests was carried out in a highly fragmented agricultural landscape in Southern Bohemia, Czech Republic, to examine whether population density or spatial distribution of active black-billed magpie (Pica pica) nests contributes to the pattern of predation on dummy nests. Out of the total of 335 dummy nests with a known fate, predators robbed 126 (37.6%). The population density of magpies did not affect nest predation significantly, while nests placed closer to active magpie nests were predated significantly more than distant nests in two out of the three years under study. Moreover, the distance to the nearest active magpie nest was found to be the most obvious factor affecting nest predation risk, among such factors as site, individual nest position, habitat type, distance to the nearest forest fragment, habitat diversity, nest concealment, distance to the nearest line habitat, and distance to a perch for avian predators. The study suggests that the spatial pattern of a dominant generalist predator can be a factor explaining the predation pattern on experimentally treated nests.
A study of home range and habitat use was carried out on grey partridge (Perdix perdix) in a high density population (24–33 pairs /km2) in the south-west part of Praha, Czech Republic from 1997 to 1999. Radiotracking of individual partridge was used in the study (n = 11). Breeding period (March – June 15) and post-breeding period (June 16 – October) were analysed separately. Home range size (minimum convex polygon 95%) in the breeding period averaged 3.7 ha with a significant increase up to 8.7 ha in the post-breeding period. The majority of partridge ranges were located within dominant crop fields and idle habitats (unmanaged early stages of plant succession) referred to as weeds. Both high population density and small individual home ranges may result from the wide availability of weeds, whose attractiveness was probably due to availability of nesting sites, sufficient food supply for both partridge chicks and adults and adequate escape cover. Despite a high population density, there is an indication of little home range overlaps between pairs during the breeding period.
Zdravá zemědělská krajina je živým organismem, otevřeným systémem s nepostihnutelným množstvím složitých vazeb, které napomáhají její stabilitě. Současný trend zemědělského hospodaření v Česku však nabízí obraz krajiny napojené na podpůrné systémy, které sice umožňují zvyšování produkce, ale za cenu rizika klinické smrti. Zemědělská krajina nežije, spíše živoří. Překotné společensko-hospodářské změny od 50. let 20. stol. po současnost se přímo odrážejí v drastické změně k horšímu v bohatství společenstev hmyzu a jejich druhové rozmanitosti. Z toho plyne již dobře pozorovatelný fatální vliv na stav samoobnovných funkcí přírody a krajiny. Stále nápadněji se projevuje neslučitelnost systému anonymních nájmů půdy s možností existence krajiny využívané s principy trvalé udržitelnosti., The healthy agricultural landscape is an open system with large numbers of stabilizing interactions. Current landscape over-exploitation entails an increased risk of ecosystem degradation. Rapid socio-economic changes since the 1950s have resulted in the decline of insect diversity, both at species and population levels. A fatal impact on self-renewable functions of nature and landscape is well noticeable., and Martin Škorpík.