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S. RösnerSascha Rösner

PhD student, editorial assistant [OECOLOGIA, Springer]

tel: +49(0)6421-2826665
sascha.roesner [-at-] uni-marburg.de

population genetics, sequencing, SSR, mtDNA, moray eel, Muraena helena, ring ouzel, Turdus torquatus, four-striped African mouse, Rhabdomys pumilio, scavengers, raven, Corvus corax, recolonisation, Tetrao urogallus, Auerhuhn, OECOLOGIA

webpage: www.sascharoesner.de

further interests: wildlife photographywebdesign

Auerhuhn | capercaillie | Tetrao urogallus
A displaying male capercaillie (Foto: pixeldiversity.com)

Wildlife management:   Capercaillies (Tetrao urogallus) in Bohemian Forest (Bayerischer Wald & Sumava National Park): The capercaillie (Tetrao urogallus) is a popular model species for the analysis of species-habitat relationships due to its large spatial requirements and its function as an umbrella species. This bird, the largest forest grouse (Tetraonidae) in the world, is endangered in Central Europe, and population numbers are declining throughout the distribution range owing to habitat fragmentation, nest predation and human outdoor activities.  The Capercaillie is mainly found in open-structured old-growth forests featuring a rich vegetation cover dominated by bilberry. However, recent studies indicate that the Capercaillie is not associated solely with old forests but also with young forests, which might also be of good habitat quality for this bird species.  In the recent work we study the capercaillie population in the Bavarian Forest which comprises one of the few remaining populations in Central Europe. We investigate a) population size by the use of genotyping, b) measure and analyze the stress load in relation to human activities (tourism in winter and summer) and c) analyze the habitat requirements and habitat suitability in the National Parks "Bayerischer Wald" and "Sumava". Furthermore d) we take a look at the endoparasite load in relation to stress load and habitat quality. We aim to work non-invasive by collecting droppings throughout the whole study area.

Project leaders: PD Dr. Jörg Müller and Sascha Rösner (National Bayerischer Wald)


DNA sampling at museum specimen (Foto: pixeldiversity.com)
Population genetics of the largest passerine Corvus corax  The raven is one of the most widespread bird species in the world. It is distributed nearly in the entire Northern hemisphere including major portions of North America, Europe, Asia and Northern Africa . Due to human persecution, the numbers and ranges of ravens declined dramatically in the middle of the 19th century. In Middle Europe, ravens originally bred in all larger forest areas. In the first decades of the 20th century more and more local populations disappeared. Finally, in the late 1920ies the raven was nearly extinct in Middle Europe. The last populations survived in three refuges, namely (i) Northern Germany and Southern Denmark , (ii) Eastern Poland and (iii) the Alps . Starting from these three refuges the recolonisation of the former range began when persecution stopped and first conservation activities (1940 - 1950) took place. Although ravens have been continually spreading for a few decades with a velocity of about 10km/y, they have not yet completely occupied their former range. At present, raven's distribution has reached the Rhine River in the West. Nevertheless, maps of the recent distribution show a gap between the Northern and Southern ranges in Central Germany . Although the data set concerning the actual raven distribution in Central Europe is quite good, the origin of the immigrated birds is not known. In our recent study, we use microsatellite DNA in order to detect cryptic genetic diversity in Middle European ravens. That may allow to make the recolonisation process more apparent. Furthermore, we would like to take a closer look at the phylogeography of the raven "species"   Corvus corax    ssp. using control region variabilities.

Project leader: Dipl.-Biol. Sascha Rösner

Ringdrosssel | ring ouzel | Turdus torquatus

Population genetics of European ring ouzel Turdus torquatus:   In 2010/2011 we initiated a population genetic study on the European thrush   Turdus torquatus. This migratory bird inhabits several low mountain ranges in Europe which are highly affected by the impact of global warming. In consequence, any upward shift caused by a risen temperature leads to decrease of available habitats and an increase in fragmentation and the low maximum altitude restricts the possibility to shift ranges upwards to escape the increase of temperature and in turn the change in ecosystems, and on the other hand the available area decreases with altitude. One of such species is the ring ouzel (Turdus torquatus). Therefore we have chosen this thrush species as a case study because it is, or was formerly distributed in the most of the middle European low, and high mountain ranges. Due to the fact that individual birds return to specific breeding and wintering areas each year, the populations in the different breeding grounds could be highly differentiated from each other. Furthermore, long time isolation of local populations might lead to the loss of single populations. This it is not only a loss of alleles but might also influence in ongoing evolution.

BIOTA-South Africa:  My activities within the BIOTA-South Africa (BIOdiversity MonitoringTransect Analysis in Africa) project focused on distribution of habitat structures in space and time, and the genetic consequences on selected model organisms of southern Africa, e.g. the four-striped mouse   (Rhabdomys pumilio). Within a collaboration with the university of Stellenbosch (South Africa) we investigate the gene flow of animal model organisms between fragments of different size and their importance for the agricultural used large areas of the fynbos and renosterveld ecosystem in the Cape region, South Africa. DNA-sequencing is used for genetic analysis.

Population genetics of Muraena helena  The moray eel Muraena helena is a reef-associated solitaire fish which belongs to the family of Muranidae . It is distributed across the eastern Atlantic Ocean southwards to Senegal within Macronesian Islands and the Mediterranean Sea. We are eager to find gene flow patterns between moray eel populations in the Mediterranean sea an the Atlantic ocean.


Kortmann, M, Heurich M, Latifi H, Rösner S, Seidl R, Müller J and Thorn S (2018): Forest structure following natural disturbances and early succession provides habitat for two avian flagship species, capercaillie (Tetrao urogallus) and hazel grouse (Tetrastes bonasia). Biological Conservation 226: 81-91.

Schabo DG, Heuner S, Neethling MV, Rösner S, Uys R, Farwig N (2016): Long-term data indicates that supplementary food enhances the number of breeding pairs in a Cape Vulture Gyps coprotheres colony. Bird Conservation International DOI: 10.1017/S0959270915000350, Published online: 12 August 2016

Rösner S, Brandl R, Segelbacher G, Lorenc T, Müller J (2014): Non-invasive genetic sampling allows estimation of capercaillie numbers and population structure in the Bohemian Forest. Eur J Wildl Res doi: 10.1007/s10344-014-0848-6

Rösner S, Mussard-Forster E, Lorenc T, Müller J (2014): Recreation shapes a “landscape of fear” for a threatened forest bird species in Central Europe. Landscape Ecology 29: 55-66.

Rösner S, Leibl F (2014): Wildtiermanagement in Nationalparken: Auerhühner im bayerisch-böhmischen Grenzgebirge. Der FALKE 7: 19-23 [ Author`s Copy].

Rösner S, Cimiotti DV, Brandl R (2013): Two sympatric lineages of the raven Corvus corax jordansi coexist on the Eastern Canary Islands. J Ornithol. doi: 10.1007/s10336-013-1006-8

Seibold S, Hempel A, Piehl S, Bässler C, Brandl R, Rösner S, Müller J (2013): Forest vegetation structure has more influence on predation risk of artificial ground nests than human activities. Basic Appl Ecol.  doi: 10.1016/j.baae.2013.09.003

Teuscher M, Brandl R, Förster B, Hothorn T, Rösner S, Müller J (2013) Forest inventories are a valuable data source for habitat modelling of forest species: an alternative to remote-sensing data. Forestry 86(2): 241-253.doi:10.1093/forestry/cps081

Bacht M, Rösner S, Müller J, Pfeifer R, Stadler J, Brandl R, Opgenoorth L (2013): Are Ring Ouzel (Turdus torquatus) populations of the low mountain ranges remnants of a broader distribution in the past? Journal of Ornithology 154: 231–237

Teuscher M, Brandl R, Rösner S, Bufka L, Lorenc T, Förster B, Hothorn T and J Müller (2011): Modelling habitat suitability for the Capercaillie   Tetrao urogallus in the national parks Bavarian Forest and Šumava. Ornithol. Anz., 50: 97–113.

Krug, C. B., Brandl, R., Boonzaier, C., Cabral, J., Esler, K. J., Grant, P. B. C., Heelemann, S., Horn, A., Keil, M., Kongor, R. Y., Meyer, J., Nottebrock, H., Poschlod, P., Reisch, C., Rösner, S., Samways, M. J., Schurr, F. M., Vrdoljak, S. (2010): Keeping the Cape Lowland archipelago afloat. - In: Hoffman, M. T., Schmiedel, U., Jürgens, N. [Eds.]: Biodiversity in southern Africa. Volume 3: Implications for landuse and management: pp. 151-179, Klaus Hess Publishers, Göttingen & Windhoek.

Teuscher, M., Brandl, R., Förster, B., Hothorn, T., Rösner, S. & J. Müller (submitted): Are forest inventory data suitable for habitat modelling? — A comparison of habitat models for Capercaillie in the Bavarian Forest National Park

Rösner, S.; Gießelmann, U.C.; Meyer, J.; Schwager, M.; Wiegand, T.; Lück-Vogel,  M. & R. Brandl (2010): Coloniality of birds in the Kalahari – spatial distribution of trees and nests of the Sociable Weaver (Philetairus socius). 

Rösner, S.; Bogatz; K.; Trapp, H.; Grünkorn, T. & R. Brandl (2010): No evidence of skewed secondary sex ratios in nestlings of the Common Raven (Corvus corax). Journal for Ornithology 150: 293-297.

Rösner, S. & C. Dietzen (2008): Ergebnisse einer zweijährigen Reviervogel-Gitternetzkartierung im Westerwald, Rheinland-Pfalz (1994/1995), Fauna und Flora in Rheinland-Pfalz Beiheft 39: 267-330.

Rösner, S. & Selva, N. (2005): Use of the bait-marking method to estimate the territory size of scavenging birds - Wildl. Biol. 11(3): 183-191.

Rösner, S.; Selva, N.; Müller, T.; Pugacewicz, E. & F. Laudet (2005): Raven Corvus corax  ecology in a primeval temperate forest. In: Jerzak, L.; Kavanagh, B.P. & P. Tryjanowski (red.): Ptaki krukowate Polski [Corvids of Poland]. - Bogucki Wyd. Nauk., Poznañ.

Rösner S. & Müller T. (2001). Der Kolkrabe Corvus corax in Hessen und Rheinland-Pfalz - Ausrottung, Wiederbesiedlung und aktueller Bestand - Charadrius 3: 109-112.

Rösner S. (2002). Räumliche Aspekte zur Aasnutzung von Kolkraben Corvus c. corax L. 1758 im Wald von Bialowieza (Nord-Ost Polen) - Master Thesis, University of Marburg, Germany. 1-86.

Müller, T. & S. Rösner (2000): Der Kolkrabe (Corvus corax) in Hessen, Wiederbesiedlung und Bestandsentwicklung. - Vogel und Umwelt 11: 3-11.

Rösner S., Dietzen C., Lippok E. (1995): Ornithologischer Jahresbericht 1994 für den Regierungsbezirk Koblenz, Fauna und Flora in Rheinland-Pfalz, Beiheft 15: 7-104.

Rösner, S. (1994): Graureiher (Ardea cinerea) und Raubwürger ( Lanius excubitor) mit bemerkenswerten Jagdstrategien. Fauna und Flora in Rheinland-Pfalz 7: 778-779.

Jönck M., Bammerlin R., Buchmann R., Lippok E., Renker C., Rösner S. (1994): Ornithologischer Jahresbericht 1993 für den Regierungsbezirk Koblenz. Fauna und Flora in Rheinland-Pfalz, Beiheft 11: 7-118.

Diploma Thesis:

Rösner, S. (2002):    Räumliche Aspekte zur Aasnutzung von Kolkraben (Corvus c. corax,   L. 1758) im Wald von Bialowieza (Nord-Ost Polen), Supervisor: Prof. H.-W. Bohle. 


Teuscher, M.; Müller, J.; Rösner, S. & R. Brandl (2010):  Are forest inventory data suitable for habitat modelling?  A comparison of habitat models for capercaillies in the Bavarian Forest. Poster at the DO-G, 143th annual meeting, 29th September – 3rd October 2010, Helgoland, Germany.

Rösner, S.; Bogatz, K.; Grünkorn, T.; Cimiotti, D., Trapp, H. &   R. Brandl (2006): Do ravens   Corvus corax   manipulate the sex ratios in their broods? Poster @ DOG - Congress, Hamburg, Germany. Vogelwarte 44: 247.

Rösner, S. & N. Selva (2006): Estimating territory of Common Ravens in Poland by bait-marking, Poster @ International ornithological Congress IOC, Hamburg, Germany.

Rösner, S.; Cimiotti, D.Meyer, J. & R. Brandl   (2006): The Common raven in Central Europe: Extinction and recolonization. Poster @ GfÖ Congress, Bremen, Germany.

Cimiotti, D.Rösner, S.Meyer, J. & R. Brandl   (2006): The Common raven in Middle Europe: Extinction and recolonization. Poster @ International ornithological Congress IOC, Hamburg, Germany.

Cimiotti, D.; Kudernatsch, D. & Rösner, S. (2006): Increasing summering of the Common Crane (Grus grus) in Southern Germany: developments, causes and predictions. Poster @ DOG - Congress, Hamburg, Germany. Vogelwarte 44: 248.


Measurement of capercaillie droppings
Does dropping size reveal capercaillie`s sex ? (Foto: pixeldiversity.com)

Tiede, Y. (2011): Does size matter? Comparison of dropping measurements and genetic analysis for sex determination in capercaillies (Tetrao urogallus).

Mussard-Foster, E. (2011, master thesis): Stress load in capercaillies (Tetrao urogallus): the influence of winter and summer tourism and forestry?

Fischl, G. (2011): Stress load in haselgrouze (Tetrastes bonasia)

Teuscher, M. (2011, master thesis): The habitat of the Capercaillie (Tetrao urogallus): insights from statistical modelling 

Bacht, M. (2010, master thesis): Genetic divergences in Ring Ouzels (Turdus torquatus) of the European low   mountain ranges

Ruhnau, C.A.S. (2009, bachelor thesis): Phylogeographic structure of the Mediterranean Moray Eel (Muraena helena)

Duarte, M.M. (2009, bachelor thesis): Genetic differentiation of small rodents in fragmented landscapes of South Africa

Glatzle, M. (2009, bachelor thesis): Habitat structure and small rodent diversity in the Renosterveld of South Africa 

Bogatz, K. (Diplomarbeit, 2009): Do ravens Corvus corax manipulate the sex ratios in their broods?

Heuck, C. (Bachelor thesis, 2008): Dispersing from refugia: expanding populations of the largest passerine: The Northern Raven (Corvus corax)

Cimiotti, D. (Diplomarbeit, 2008): Phylogeographic patterns in the Northern Raven (Corvus corax) across the Western Palaearctic and Greenland: are there several subspecies? 


Seminar for bachelor of science students: Macroecology: linear and multiple regression analysis with R (The R project for statistical computing

Seminar: Forest ecology courses (animal ecology)

Students excursion: Forest ecology - Eastern Poland, Bialowieza National Park September 2005 (initiation, concept, accomplishment and  guiding)

Statistic course and excursion for PhD students: Applied statistics in Ecology - using R (The R project for statistical computing) - May 2008, Bialowieza, Poland (initiation, concept, accomplishment and  guiding)



Gesellschaft für Ökologie: www.gfoe.org

Deutsche Ornithologen Gesellschaft:  www.do-g.de

Gesellschaft für Naturschutz und Ornithologie in Rheinland-Pfalz: e.V. www.gnor.de

Hessische Gesellschaft für Naturschutz und Ornithologie e.V.: www.hgon.de

Ornithologische Gesellschaft Bayern e.V.: www.og-bayern.de

Zuletzt aktualisiert: 24.08.2018 · Sascha Rösner

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