Factors Regulating Local Variations in Abundance: Field Tests on Hedgehogs, Erinaceus europaeus

This paper reports the results of a field experiment to identify factors regulating local variations in population sizes of a common insectivore. A low density population of hedgehogs Erinaceus europaeus was artificially increased in numbers while simultaneously a high density population was reduced. Subsequent dispersal, mortality and natality were monitored in complete censuses of the total populations, and compared to a control population of transplanted hedgehogs at unchanged density. Predation on hedgehogs was principally by badgers Meles meles which forage for substantially similar foods to hedgehogs, and was significantly higher in the expanded population during the first 2 wk after transplant than in the control, which nevertheless suffered a high overall mortality