부산대학교 도서관

Most of the changes in land use have led to a decline in the biodiversity of agricultural land. Extensive perennial alfalfa fields favor the proliferation of agricultural pests, especially common voles. However, rodents can damage not only the plants but also the nests of passerines that breed on the ground. Their seasonal and annual dynamics influence the breeding success of ground nesting passerines, thereby influencing their global populations. We assumed that the number of rodents is higher on perennial alfalfa fields and the ground nests of passerines breeding there are less likely to survive than on a newly established field. Furthermore, we also presumed that the predation pressure inside the plots is lower than at their edges, as more rodents tend to be at the edges of the plots and in the hedges. We tested our hypotheses by trapping small mammals and using artificial ground nests with plasticine and quail eggs. The survey was carried out in the spring of 2017 on large plots of agricultural land in the southern part of Hungary, near the Croatian state border, in the vicinity of Püspökbóly settlement. Contrary to our expectations, the abundance of small mammals was similar in two-year-old (3 individuals per 100 trap nights) and one-year-old (2.5 ind. per 100 trap nights) alfalfa fields. The majority of rodents (more than 86%) were caught near the edges of both plots. The nest predation study lasted for two weeks as the incubation time for ground nesting passerines. From the total of the 80 nests, only in 14 artificial nests (17.5%) was a predation event observed. At the edge of the two plots, where the abundance of rodents was high, the survival chances of the ground nests were similar. In contrast, the daily survival rate of ground nests inside the two-year-old alfalfa plot (99%) was significantly higher than in the one-year-old one (96%). The daily survival rates of nests inside and at the edges of the plots were similar. Besides the small mammals, the nests were also predated by red foxes and birds, therefore there were no differences between the predation activity of rodents and the survival of eggs in artificial ground nests.