Senckenberg Research Institute and Natural History Museum Frankfurt



Scinax fuscovariusD melH puns madD leu

M Jansen

Internal links                                                                                                             

Research Station Chiquitos, Bolivia

Integrative guide to the frogs of the Chiquitano region

Snakes of Bolivia

Phone: +49 (0)69 7542-1234

Bachelor- und Masterarbeiten zu vergeben! Hier klicken                                                                                              

Themenbereiche: Bioakustik, automatisiertes akustisches Monitoring, innerartliche und zwischenartliche Variationen, Verhaltensökologie.

Studenten der Biologie und Bioinformatik, Lehramtsstudenten der Biologie und Mathematik.

Research interests/current works

I am a herpetologist and field biologist. My main research interests include taxonomy, diversity, bioacoustics, acoustic communication, behavioral ecology, and evolutionary biology. My focal taxa are Neotropical frogs and snakes. Regarding methodology, I am currently developing protocols for the automated recording and detection of frog calls for the use in taxonomy (species delimitation), behavioral ecology, as well as conservation.

Call variation, calling effort and contest behavior of Leptodactylus frogs


For many animal species, especially frogs, acoustic communication is essential for species recognition, mate choice or territorial behavior. However, _mce_only a few studies on anuran communication take into account the complete call effort and call repertoire, respectively  their temporal variation throughout and across nights, yet examining call behavior at that scale is essential for both species delimination and understanding  the role of selection in evolutionary change.

Recent developments in passive acoustic monitoring and acoustic pattern recognition now enable us to comprehensively record and analyze acoustic events over longer periods of time. In this project we study the call variation of white-lipped frogs (Leptodactylus) during sustained calling over several nights using passive acoustic recordings, IR-cameras, software for the automated detection of acoustic signals, and the statistic software R (“Big data become smart data”, see my Blog-Entry [German only]).

Specific aims of the project:

  • documentation of the absolute calling effort of Leptodactylus frogs
  • analyzing temperature effects on variation of specific call parameters, as well as calling “management”
  • assessing the absolute acoustic space for species delimitation in Leptodactylus frogs
  • developing monitoring methods for conservation management of frogs

Collaborators: Anastasia Masurowa (master student, University of Mainz), Bob O´Hara (Senckenberg Biodiversity and Climate Research Institute), Arne Schulze (Landesmuseum Darmstadt), Amanda Lea (University of Texas at Austin)

Funding and Support: Wilhelm-Peters-Fond (Deutsche Gesellschaft für Herpetologie und Terrarienkunde), Paul Ungerer Stiftung (Frankfurt). Globetrotter Ausrüstungen (Shop Frankfurt)


Recent publications of the project

Jansen, M., A. Masurowa & R. O´Hara (2016): Temporal variation, duty cycle and absolute calling effort during sustained calling of Leptodactylus mystacinus (Anura: Leptodactylidae). Salamandra (in press)

Jansen, M., A. Masurowa & R. B. O´Hara (2015): Individuality in the face of plasticity: signal variation during sustained calling in frogs. Poster at the 25 International Bioacoustrics Congress, 7-12 September 2015, in Murnau, Germany.

Martin Jansen & Bob O´Hara (2014): Exploring the call management of frogs through automated bioacoustics monitoring. Ecoacoustics - Ecology and acoustics: emergemnt properties from community to landscape. Muséum national d`Histoire naturelle, Paris, France, 16-18 June 2014.


Fig: 1: Recording device SongMeter® used for longtime recordings (left), and infrared-camera setting to monitor Leptodactylus syphax, which associated with granite outcrops.

varls ir 

Fig 2. Left: Nightly variation of dominant frequency (upper graph) and call duration in one specimen of Leptodactylus syphax. Right: Screenshot of infrared video sequence of Leptodactylus syphax. A 30 second sequence can be seen here.

Integrative taxonomy of Neotropical Herpetofauna

By combining different disciplines and methods, such as morphology, bioacoustics and molecular methods I try to assign species, detect candidate species, and search for trait evolution. Of particular interest is the integrative taxonomy of frogs in Bolivia (e.g. Jansen et al. 2011, Jansen & Schulze 2012, Schulze & Jansen 2012, Schulze et al. 2015). Currently, I work on several taxonomic revisions in collaborations, concerning the following genera: Leptodactylus, Dendropsophus, Proceratophrys, Pseudopaludicola,  Rhinella, Scinax (Anura); Bothrops (Squamata). The use of bioacoustics as a tool of taxonomy, i.e. its power and limitations, is of particular interest (multi-authors work in prep.).

Pseudis paradoxaD_meld-mü

 Fig. 3: Tadpoles of Pseudis paradoxa, Dendropsophus melanargyreus, and Dermatonotus mülleri (Schulze et al. 2015)

Taxonomy: Description of new species and revisions                                                                                                         

Scinax villasboasi (Brusquetti, Jansen, Barrio-Amorós, Segalla & Haddad 2014)

Scinax madeirae (removed from synonymy of Scinax fuscomarginatus, Brusquetti, Jansen, Barrio-Amorós, Segalla & Haddad 2014)

Hydrolaetare caparu (Jansen, Gonzales &. Köhler 2009)

Xenopholis werdingorum (Jansen, Gonzales & Köhler 2009)

Phalotris sansebastiani (Jansen & Köhler 2008)

Call evolution in frogs: Asymmetric frequency shift in advertisement calls of sympatric frogs

Character displacement is commonly observed when species occur in secondary contact zones and traits related to resource competition or reproduction diverge in sympatry. We studied displacement in advertisement calls in two species of hylid frogs from allopatric and sympatric populations, both of which call with similar frequencies but differ substantially in temporal parameters. We found asymmetrical character displacement in sympatry, as only Scinax madeirae (but not S. fuscomarginatus) repeatedly showed displacement. We explored possible reasons for this specific pattern concerning the displaced characters and tested if socio-functional constraints in specific call parameters are responsible for the shift of only spectral parameters in that species. Finally, we argue that the simultaneous action of ecological and reproductive character displacement, or alternatively, a short-term behavioral response for the same reason (avoidance of hybridization) could explain the pattern. The present study identifies a set of new hypotheses that will stimulate future research on mechanisms of mate recognition and behavioral responses.

Jansen, M., M. Plath, F. Brusquetti & M. Ryan (2016): Asymmetric frequency shift in advertisement calls of sympatric frogs. Amphibian-Reptilia (online first)

jansen et al fig 6 


fig 4

Fig. 4: Within-male call variation CVwi in Scinax madeirae and S. fuscomarginatus (41 individuals; 313 calls). Taken from Jansen et al. (in press).


Fig. 5: Above: Lateral view of larynx of Scinax madeirae;  calling Scinax madeirae from Bolivia.Taken from Jansen et al. (in press).

Bioacoustic monitoring – documentation of “soundscapes”

At our research station in Bolivia we conduct monitorings at different sites with several waterproof longtime recorders. The next step will be to develop detection and analyzing methods to handle this “big data” (meanwhile terrabytes of recordings of multispecies-choruses), and to study calling phenology (i.e. the beginning and end of calling throughout the night and season) and its abiotic and biotic influences on calls of selected species.


Fig. 6: The Research station "Chiquitos" and bioacoustic monitoring device nearby.

Scientific publications (peer-reviewed articles 2007-2016)


Jansen, M., A. Masurowa & R. O´Hara (2016): Temporal variation, duty cycle and absolute calling effort during sustained calling of Leptodactylus mystacinus (Anura: Leptodactylidae). Salamandra (in press)

Jansen, M., M. Plath, F. Brusquetti & M. Ryan (2016): Asymmetric frequency shift in advertisement calls of sympatric frogs. Amphibian-Reptilia (online first)


Schulze, A., Jansen, M. & G. Köhler (2015): Tadpole diversity of Bolivia`s lowland anuran communities: molecular identification, morphological characterization, and ecological assignment. Zootaxa 4016(1):1-111.


Gehara, M.,  Crawford, A. J., Orrico, V. G. D., Rodríguez, A., Lötters, S., Fouquet, A., Barrientos, L. S., Brusquetti, F., De la Riva, I., Ernst, R., Urrutia, G. G., Glaw, F.,  Guayasamin, J. M., Hölting, M., Jansen, M., Kok, P. J. R., Kwet, A., Lingnau, R., Lyra, M., Moravec, J., Pombal Jr., J. P., Rojas-Runjaic, F. J. M.,  Schulze, A., Celsa Señaris, J., Solé, M., Rodrigues, M. T., Twomey, E., Haddad, C. F. B., Vences, M. and Köhler J. (2014 ). High levels of diversity uncovered in a widespread nominal taxon: continental phylogeography of the Neotropical tree frog Dendropsophus minutus. 2014. Plos One, 10 September 2014.

Brusquetti, F., Jansen, M., C. Barrio-Amorós, Magno Segalla & C. F. B. Haddad (2014): Taxonomic review of Scinax fuscomarginatus (Lutz, 1925) and related species (Anura; Hylidae). Zoological Journal of the Linnean Society, 171, 4: 783-821

Jansen, M. & Schulze: Molecular, morphology and bioacoustic data suggest Bolivian distribution of a large species of the Leptodactylus pentadactylus group (Amphibia: Anura: Leptodactylidae). Zootaxa 3307: 35-47.

Schulze, A. & M. Jansen: One species, two strategies? Oviposition site variation in a member of the Leptodactylus pentadctylus group (Amphibia: Anura: Leptodactylidae) Studies on Neotropical Fauna and Environment, DOI:10.1080/01650521.2012.711102

Jansen, M. R. Bloch, A. Schulze & M. Pfenninger: Integrative inventory of Bolivia’s lowland frogs reveals hidden diversity. Zoologica Scripta 40(6): 567-583.

Schulze, A. & M. Jansen: A tadpole of Trachycephalus venulosus (Anura: Hylidae) as prey for a fishing spider (Araneae: Pisauridae) in the Bolivian Chiquitano Dry Forest. Herpetology Notes 3: 297-298.

Jansen, M. & G. Köhler: Reptilia, Squamata, Amphisbaenidae, Amphisbaena cegei Montero, 1997, and Reptilia, Squamata, Teidae, Tupinambis rufescens (Günther, 1871): vertical range extension. CheckList 6(4): 503-504.

Mebs, D., M. Jansen, G. Köhler, W. Pogoda & G. Kauert: Myrmecophagy and alkaloid sequestration in amphibians: A study on Dendrobatidae (Ameerega picta) and Microhylidae (Elachistocleis sp.) frogs. Salamandra 46(1): 11-15.

Jansen, M., A. Schulze, L. Werding & B. Streit: Effects of extreme drought in the dry season on an anuran community in the Bolivian Chiquitano region. Salamandra 45(4): 233-238.

Jansen, M., L. Gonzales & G. Köhler: Description of a new species of Xenopholis (Serpentes: Colubridae) from the Cerrado of Bolivia with comments on Xenopholis scalaris in Bolivia. Zootaxa 2222: 31-45.

Jansen, M.: Measuring temporal variation in calling intensity of a frog chorus with a  data logging sound level meter: A case study in Bolivia. Herpetology Notes 2: 143-149.

Schulze, A., Jansen, M. & G. Köhler: Diversity and ecology of an anuran community in San Sebastián, Bolivia. Salamandra 45(2):75-90.

Jansen, M.: New and noteworthy records of snakes from Bolivia. Herpetological Review 39(3): 374-375.

Jansen, M & G. Köhler: A new species of Phalotris (Reptilia, Squamata, Colubridae) from the eastern lowlands of Bolivia. Senckenbergiana biologica 88: 103-110.

Jansen, M & J. Köhler: Intraspecific combat behavior of Phyllomedusa boliviana (Anura: Hylidae) and the possible origin of visual signaling in nocturnal treefrogs. Herpetological Review 39(3): 290-293.

Jansen, M., L. Gonzales & G. Köhler: New species of Hydrolaetare (Anura: Leptodactylidae) from Bolivia with some notes on its natural history. Journal of Herpetology 41(4): 724-732.

Jansen, M & J. Köhler: Description of the advertisement call of Eleutherodactylus fraudator. South American Journal of Herpetology 2(3): 198-200.