Reproduction characteristics of wild boar (Sus scrofa) in Lower Saxony, Germany I nstitute for Wildlife Research at the University for Veterinary Medicine, Foundation Friederike Gethöffer, Denise Neubauer, Oliver Keuling and Gunter Sodeikat I ntroduction and aims Population dynamics of wild boar Sus scrofa in Western Europe result in sophisticated discussions, considering the spreading of classical swine fever (CSF) among high wild boar population densities as a main concern. Hunting bag statistics indicate that piglets represent the main part of the wild boar population nowadays. That gives evidence of a high turn-over-rate of the steadily increasing populations, which enhances the spreading of CSF among wild boar. In order to create management tools and to model population dynamics, it is necessary to investigate the current reproductive performance of wild boar. It is therefore the aim of this study to allow a current evaluation of the reproductive potency of wild boar in an area that represents exemplary habitats for wild boar in central Europe. Besides, the seasonality of reproduction as well as the share of the different age classes on the potential reproductive outcome of wild boar populations in the eastern part of Lower Saxony/ Germany is inquired. Study area and methods During seven years of study (2003 – 2009), samples (consisting of ovaries and uteri from wild boar) have been taken from areas in Eastern Lower Saxony in which vaccination against CSF among wild boar provided the fight against several outbreaks of the disease. The study site is situated in the plains of Northern Germany (Fig. 1). The area comprises about 50% wood and 50% farmland. The percentage of deciduous trees, especially oak ( Quercus robur and Q. borealis) and beech ( Fagus sylvatica ), does not exceed 10% . Hunting bag of wild boar in these sites ranged from two to four individuals per 100 ha during the last years. year number of samples age class ovulation rate mean number of fetuses 2003/ 04 N=384 piglets 5,45 5,67 yearlings 7,67 6,70 adults 8,19 7,33 2004/ 05 N=467 piglets 6,40 6,75 yearlings 7,14 6,5 adults 8,46 8,00 2005/ 06 N=154 piglets 5,00 -* yearlings 6,75 7,00 adults 8,17 6,67 2006/ 07 N=207 piglets 7,30 6,33 yearlings 7,62 7,79 adults 6,56 7,88 2007/ 08 N=334 piglets 5,29 4,83 yearlings 6,81 6,8 adults 7,70 8,25 2008/ 09 N=226 piglets 5,33 5,00 yearlings 7,25 6,25 adults 7,82 7,17 2003-2009 N=1772 piglets 5,78 5,52 yearlings 7,32 7,05 adults 7,74 7,59 Conclusions and outlook Wild boar populations in central Europe rely on optimal environmental conditions. This is reflected in an increase of the population and based on an improvement of its reproductive performance as well as its adjustability to new habitat types. The results underline the necessity of wild boar management that considers the social structures of this species and may additionally serve as a basis for population models. It is indicated that extrinsic factors influence wild boar reproduction even under an optimum of environmental conditions. The outcome of this study further gives evidence of an early onset of puberty combined with a high reproductive output among wild boar piglets. Considering the risk of epidemics connected with the current social structures of wild boar populations, the main target of the future management of wild boar should be a reduction of piglets, e.g. by intense hunting pressure. Table 1: Parameters of wild boar reproduction in different age classes (2003 – 2009) Authors address: Institute for Wildlife Research at the University of Veterinary Medicine Hannover, Foundation Bischofsholer Damm 15, D-30173 Hannover, Germany e-mail: friederike@gethoeffer.de gunter.sodeikat@tiho-hannover.de Tel.: +49 511 856 7567 Fax: +49 511 856 7696 Preliminary results About 1800 samples have been collected during main hunting seasons from drive hunts. Piglets of an approximate age of 8 month own a 76% chance to already have gained sexual maturity. Between 60% and 70% of the piglets most likely get pregnant during the main period of reproduction, while another two thirds of the remaining individuals farrow until summer. Mean number of foetuses outrage formerly known values with 5.5 per piglet, 7.1 per yearling and 7.6 per adult as an arithmetic mean for wild boar (Tab. 1). Although serum diagnostics confirmed the prevalence of porcine parvovirosis and Aujeszky´ s disease in the area, examination of the uteri revealed very few organic aberrations that might be due to a response to these diseases. High participation of yearlings and older animals in reproductive performance resulted in pregnancy prevalences of about 100% of the individuals during January 2009. Wildtier-Informationssystem der Länder Deutschlands Figure 1: Location of study area within Germany red colour indicates mean HI of wild boar within German administrative districts (2002-2007) HI (shot animals /km²) 0.0 >0.0-0.25 >0.25-0.5 >0.5-1.0 >1.0-2.0 >2.0-3.0 >3.0