Abundance of the European hare (Lepus europaeus Pllas, 1778) has been declining dramatically in Europe. In the framework of our long-term ecological studies in the juniper forest at Bugas, Hungary, we have also monitored its population abundance. At the ginning of our researches the European rabbit (Oryctolagus cuniculus Linné, 1758) had been the dominant herbivore species there, but as a result of two diseases in 1994 and 1995 they disappeared. Earlier studies had showed competition between these two species, therefore we expected a significant increase in the local hare abundance after the extinction of rabbits. Our results, however, did not comply with this supposition. Nonetheless, experimental comparison of the vegetation in grazed and ungrazed plots proved that rabbits had been significantly decreasing the vegetation cover, especially that of grasses; meanwhile hares did not. Although grasses were the main food components of both species, their moderate diet overlap throughout the year does not suggest a food competition between them. All these findings show that population size of hares was not significantly limited by rabbits due to trophic overlap. Competitive effect of rabbit on sympatric hares had been low or it was expressed by the depreciation of other non-investigated population characteristics.
We investigated how the sampling process of microhistological faeces analysis could be optimised for an accurate estimation. Spring diet composition of European hare (Lepus europaeus Pallas, 1778) was determined in a juniper shrubland at Bugac, Hungary. Both inter and intraobserver reliability was high permitting us to separate the components of variance due to the methodological steps in the faeces analysis. Estimates varied depending on the number of independent droppings, pellets/individual, subsamples/pellet and epidermis/subsample. The variance was much higher among than within the independent pellet groups. The cumulative frequency estimate stabilised at around 100 epidermis fragments per pellet. We conclude that the most critical steps of the sampling procedure are the collection of independent droppings and the identification of a sufficient number of epidermis fragments. We propose to collect at least 10 independent droppings, one pellet/individual, and analyse 100 epidermis fragments as an optimum for estimating the relative frequency of forage classes reliably. The importance of the individual variability in the diet should be emphasised.