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The German Wildlife Information System, founded in 2001, is a long-term monitoring program documenting occurrence, number, and development of game populations throughout Germany. Population numbers are recorded by standardized counting methods in so-called reference areas. The population densities of the European hare are calculated by spotlight strip censuses in the reference areas each spring and autumn all across Germany. From 2002 to 2005, the censuses were carried out by local hunters in 510 to 676 reference areas each year. During these years, the calculated spring densities increased significantly from 11.0 (2002) to 14.5 hares/km 2 (2005) nationwide. The overall increase in spring densities was primarily caused by the population rise from spring 2003 to 2004, which correlates with the high net growth rate in 2003. In 2005, the number of counted hares varied between less than 1 and more than 107 hares/km 2 in spring and between 0 and more than 170 hares/km 2 in autumn. Because of differing landscapes in Germany, three regions were differentiated. In spring 2005, the average population densities (median) in East Germany (5.4 hares/km 2 ) and Southwest Germany (14.6 hares/km 2 ) were significantly lower than in Northwest Germany (23.9 hares/km 2 ). These regional differences had been similarly distinct in former years.

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Monitoring the populations of badgers and red foxes may help us to manage these predator species as a matter of wildlife conservation and regulation. To fit the needs of a monitoring programme, the most practicable method has to be selected. Hunting bag statistics deliver large but inaccurate data amounts with low effort. Indirect and also often direct counts might deliver only presenceabsence data with high effort. Direct counts with high accuracy are very costly. Den mapping by volunteer local hunters can deliver reliable data on density and additional biological variables while being feasible and cost effective. Within reference areas all over Germany, fox and badger dens and litters were recorded, and spring and summer densities estimated as well as potential annual population increases were calculated for 2003-2007. Habitat preferences for breeding dens were also analysed. Additionally, in 2006, the distribution of badgers was surveyed by a nationwide questionnaire. Fox and badger are distributed all over Germany with some small gaps and regionally differing densities. During the monitoring period, fox and badger densities and reproduction stayed stable, at a high level corresponding to hunting bags. However, densities varied between geographical regions, with lower densities in the sparsely wooded lowland regions. A preference for forest and habitats offering shelter was clear for breeding setts and dens. Badgers especially preferred setts of natural origin.

Background The European brown hare ( Lepus europaeus ) typically resides in open habitats in agriculturally dominated landscapes in Europe. Over recent decades, a widely observed population decline occurred, which was attributed to agricultural intensification. However, with political incentives for specific crops, especially maize for energy production, the habitat went through massive changes. Thus, there is the need to identify parameters that characterize a suitable habitat for the brown hare in today’s agricultural lands. Results We modelled European brown hare densities spatially and temporally explicit over 10 years (2005–2014) across an entire federal state. The generalized additive mixed model confirms a constant decline of the European brown hare population in Lower Saxony. Municipalities with a high proportion of grassland and precipitation totaling up to 900 mm are more favored. Woodland showed an approximately linear negative effect. The most important agricultural crop groups such as winter grains and winter oilseed rape showed overall positive effects on hare densities. However, the effect of maize was unimodal, with a positive effect of medium proportions, but a negative effect of very high proportions. The effect of sugar beet was relatively weak but negative. Brown hares were also more abundant in municipalities with a higher density of vixen with litter and municipalities with a high proportion of wildflower strips showed higher brown hare abundance. Conclusion Lower Saxony is a diverse federal state with grassland dominated areas in the northwest, more woodland in the east, but intensive arable land in most remaining areas. The European brown hare—a species with a wide ecological potency—shows preferences to both grassland and the most typical arable crop groups such as winter grains and winter oilseed rape. The substantial increase in maize production within the time frame was likely unfavourable and may be one reason for the decline. Nonetheless, political tools such as the agri-environmental scheme “wildflower strips” were beneficial for the brown hare abundance and may be an option to reverse the decline seen over the 10 years. Electronic supplementary material The online version of this article (10.1186/s12898-019-0247-7) contains supplementary material, which is available to authorized users.