Long-term Population Trends on Brown Hare in Intensively Used Agricultural Landscape, Lower Saxony, Northern Germany

Transcription

1 Long-term Population Trends on Brown Hare in Intensively Used Agricultural Landscape, Lower Saxony, Northern Germany Egbert Strauss 1,2, Ulrich Voigt 1, Inga Klages 1,2, Katrin Ronnenberg 1 1 Institute for Terrestrial and Aquatic Wildlife Research University of Veterinary Medicine Hannover, Foundation 2 Hunting Association of Lower Saxony The project is supported by funds of the Lower Saxony Ministry of Food, Agriculture and Consumer Protection.

2 How many are we? objectives monitoring of hare populations on different scales and on different methods comparison on survey and census data set census and survey in Lower Saxony wildlife survey since 1991 spotlight counts (hares) since 1994 hunting bag since 1958

3 Wildlife survey data annual questionnaire on several game species ~ 9,200 private hunting grounds and 150 state forest districts are questioned annually about: occurrence abundance diseases hunting management hunting bag opinion piclease Brillen piclease Ott piclease Brillen piclease Ott piclease Lettow piclease Kaminski participation : % = 7,600 8,500 hunting grounds managed by: Hunting Association of Lower Saxony scientific research: Institute for Terrestrial and Aquatic Wildlife Research piclease Müller piclease Gailberger

4 Study Region Lower Saxony 48,000 km² 9,200 hunting grounds intensive agriculture

5 Study Region Lower Saxony North-West German Lowland forest: app. <10 % high soil quality wheat, maize, grassland Lüneburg Heath forest: app. 33% low soil quality maize, rape, barley Börde forest: app. <10 % very high soil quality wheat, maize, sugar beet, rape Weser and Harz Mountains forest: app. 33% low mountain range ( m ASL) middle soil quality wheat, maize, rape

6 Hare Population assessed hare population in 7,500 to 8,200 hunting grounds 2006 Ems-Weser-Marsch Ostfriesl, Oldbg & Osnab. Raum Elbe-Niederung Börde & Weser-Aller-Flachland Stader Geest & Heide Weserbergland & Harz N Hares / km² 20 Geometrische Grundlage: Nds. Landesamt für Ökologie - Geosum (Geosumserver Nds. Umweltministerium, Stand: 2002) Km

7 Hare Population assessed hare population in 7,500 to 8,200 hunting grounds Ems-Weser-Marsch Ostfriesl, Oldbg & Osnab. Raum Elbe-Niederung Börde & Weser-Aller-Flachland Stader Geest & Heide Weserbergland & Harz Hares / km² Datenquelle: Wildtiererfassung Niedersachsen (WTE), Landesjägerschaft Niedersachsen e.v., gefördert durch Jagdabgabemittel des Landes Niedersachsen Kartografische Grundlage: GeoBasis-DE / BKG km ±

8 Census spotlight counting in randomly selected hunting grounds nach SALZMANN-WANDELER & SALZMANN 1973, PFISTER & RIMATHE 1979, PEGEL in spring and autumn counts per season - range of spotlight ca. 150 m - lighting area min. 200 ha

9 Hare population spotlight counts in 5 study areas n hares / km²

10 Survey versus Census comparison on hare population by wildlife survey and spotlight counting 2016 Box plot: estimated hare population of hunting grounds of 5 counties Lines: spotlight counted hare population in 5 randomly selected study areas n hares / km² n = 72 n = 130 n = 92 n = 235 n = 108 LK WTM LK BRA LK PE LK H LK HM

11 Summary currently hunting bag are not representative of population densities relative high population densities (20 60 hare/km²) in intensively used arable and pasture land high variances and strong population fluctuations in local population densities in some regions high increase, after 2006 strong decline in regions with lower population densities moderate fluctuations

12 Conclusion hunters can provide cost-effective, long-term and reliable monitoring data by scientific guidance = citizen science important for scientific studies on large scales causes of the fluctuations mainly are unknown census data of small sample size limited representativeness, due to high variances and fluctuations of the populations hunting management must be based on valid data

13 Thank you for your attention