Investigation of possible influencing factors on the population density offield hares

During the years 1994 to 1996 the study group for wildlife biology carried out an,Investigation Program for Field Hares" commissioned by the Hessen Ag ricultural Ministry. The investigation project was conducted in cooperation with the State Hunting Association of I Iessen e.V., and the State Medicin al. Food. and Veterinary Administration of Middle Hessen. In the various re gions of Hessen very different autumn densities were determined varying bet ween 11.0 to 145.3 hares/100 ha. Substantial differences in the proportions of young hares were found between the regions having below and above avera ge densities as the numbers of young harts were significantly reduced in po or hare regions. On the basis of histological examinations of the testes th e surmise of reduced spermiogenesis in districts with below average densiti es was revised through further investigations and proved to be seasonally v ariable. Hence this is not a demonstrable proof of infertility among male h ares. As the first investigations of the uteri of shot field hares show tha t a sufficient large number of fetuses (on average 7-8 per female) were the re, the variability in the proportions of young harts in the different regi ons must be caused Ly differing mortality losses. These losses are mainly t he result of intensive farming techniques accompanied by a greater or lesse r reduction in habitat diversity with the consequence of inadequate living conditions fur the young hares in the first few weeks.