The feeding area selection of the common crane was studied between 1996–1998 in the Hortobágy National Park and surrounding areas during the autumn migration and staging over period. The cranes roosted in marshlands and drained fishponds and fed in the following types of agricultural areas: maize stubble, maize-, wheat-, alfalfa-, and abandoned fields as well as natural grasslands. The largest proportion of crane flocks fed on maize stubbles on waste grain. Family flocks usually fed separately. The type of feeding area did not depend on the time of the day. The density of feeding flocks did not depend on the type of feeding area, indicating high abundance of food. The study suggests that agricultural areas inside the National Park should be used for growing maize for staging cranes in order to attract them from disturbed non-protected arable lands outside the National Park. It is also important to stop wildfowl-hunting in fishponds to let cranes choose between more roost sites closer to feeding areas.
Cannibalism, the act of eating an individual of the same species has been little studied in omnivorous insect predators. Dicyphus errans (Wolff) (Hemiptera: Miridae) is a generalist omnivorous predator that commonly occurs in tomato greenhouses and field crops in the Mediterranean basin. In this work cannibalism among same-aged neonate nymphs of D. errans was studied when 1, 2, 4, 8 or 16 individuals were placed in a Petri dish along with or without heterospecific prey. Although nymphs were unable to complete their development in the absence of prey they survived longer when there were initially 2 individuals per dish than in any other treatment including a single individual. This may indicate that cannibalism in this predator has positive effect on nymphal survival, which however was not the case at higher densities. The presence of heterospecific prey increased nymphal survival and individuals were as equally successful in completing their development as when kept singly. Developmental time in all the treatments was very similar. Adult weight of both females and males was significantly greater when a nymph was reared alone and similar in all the other treatments. The results indicate that cannibalism occurs among neonates of D. errans if heterospecific prey is scarce and has a negative effect on adult weight when heterospecific prey is abundant. This should be considered in studies on enhancing the biocontrol efficiency or mass rearing of this predator.
The diet of the otter (Lutra lutra L.) was assessed through spraint analysis at three different streams in the Beskydy Mountains (north-east Czech Republic) and compared with fish availability and river management procedures. The remains of 3 478 prey items were recorded in 894 spraints, collected between May 2000 and May 2002. Fish were the dominant species taken (90%), followed by amphibians (50%). The most frequently occurring species of fish were the Carpathian sculpin Cottus poecilopus (71%) and brown trout Salmo trutta m. fario (65%). The composition of the otter’s diet tended to reflect the fish availability (biomass) in streams. Despite the general similarity of the different streams studied, diet composition differed significantly. The differences in diet could be explained by differences in fishery management (stocking) together with the location of migration barriers.