Abundance of the European hare (Lepus europaeus Pallas, 1778) has been declining dramatically in Europe. In the framework of our long-term ecological studies in the juniper forest at Bugac, Hungary, we have also monitored its population abundance. At the beginning 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.
Katona K, Bíró Zs, Hahn I et al: Competition between European hare ... (2004)
Katona K, Bíró Zsolt, Hahn István, Kertész Miklós, Altbäcker Vilmos
Competition between European hare and European rabbit in a lowland area, Hungary: a long-term ecological study in the period of rabbit extinction.
Folia Zoologica 53: 255-268