Norrdahl Kai, Korpimäki Erkki
Department of Zoology, Division of Ecology, University of Helsinki, P.O. Box 17, FIN-00014, Finland.
Laboratory of Ecological Zoology, Department of Biology, University of Turku, FIN-20500, Turku, Finland.
Oecologia. 1995 Aug;103(2):241-248. doi: 10.1007/BF00329086.
We studied the effects of removal of breeding nomadic avian predators (the kestrel, Falco tinnunculus and Tengmalm's owl, Aegolius funereus) on small mammals (voles of the genera Microtus and Clethrionomys and the common shrew, Sorex araneus) during 1989-1992 in western Finland to find out if these predators have a regulating or limiting impact on their prey populations. We removed potential breeding sites of raptors from five manipulation areas (c. 3 km each), whereas control areas had nest-boxes in addition to natural cavities and stick-nests. Densities of small mammals were monitored by snap-trapping in April, June, and August, and densities of mammalian predators (the least weasel, Mustela nivalis nivalis, the stoat, M. erminea and the red fox, Vulpes vulpes) by snow tracking in early spring and late autumn. The yearly mean number of raptor breeding territories was 0.2-1.0 in reduction areas and 3.0-8.2 in control areas. Breeding raptors alone did not regulate prey populations in the long term, but probably caused short-term changes in the population dynamics of both the main prey, the sibling vole (Microtus rossiaemeridionalis) and an alternative prey (the common shrew). The densities of an alternative prey, the bank vole (Clethrionomys glareolus) decreased in raptor reduction areas, most likely due to increased least weasel predation pressure in the absence of breeding avian predators.
1989年至1992年期间，我们在芬兰西部研究了去除繁殖期的游牧性鸟类捕食者（红隼，矛隼和长耳鸮，鬼鸮）对小型哺乳动物（田鼠属和田鼠属的田鼠以及普通鼩鼱，赤齿鼩鼱）的影响，以确定这些捕食者是否对其猎物种群具有调节或限制作用。我们从五个操作区域（每个区域约3公里）移除了猛禽的潜在繁殖地点，而对照区域除了天然洞穴和树枝巢外还有巢箱。通过在4月、6月和8月进行快速诱捕来监测小型哺乳动物的密度，并在早春和深秋通过雪地追踪来监测哺乳动物捕食者（伶鼬，伶鼬指名亚种、白鼬，艾鼬和赤狐，赤狐）的密度。减少区域中猛禽繁殖领地的年平均数量为0.2-1.0，对照区域为3.0-8.2。仅繁殖期的猛禽从长期来看并不能调节猎物种群，但可能会导致主要猎物同胞田鼠（南欧田鼠）和替代猎物（普通鼩鼱）种群动态的短期变化。在猛禽减少区域，替代猎物棕背田鼠（棕背田鼠）的密度下降，最有可能是由于在没有繁殖期鸟类捕食者的情况下，伶鼬的捕食压力增加。
