Abstracts - Deutsche Zoologische Gesellschaft

Behavioral Biology Symposium 25O BB.5 (Su) - ENWhy do shrews call?Sophie von Merten 1 , Grit Schauermann 2 , Hendrik Turni 3 , Björn M. Siemers 11Sensory Ecology Group, Max Planck Insitute for Ornithology, Seewiesen; 2 Animal Physiology,University of Tübingen; 3 Museum für Naturkunde der Humboldt-Universität, BerlinShrews are very vocal animals. While some vocalisations serve interspecific communication, it isnot yet clear why they produce twittering calls during solitary exploration. One hypothesis is the useof a simple echolocation-like system for orientation. Shrews mainly forage in cluttered substrate.Thus, they could use echoes of their calls to assess the habitat structure at close range, but beyond therange of their vibrissae. A series of classical studies provide equivocal evidence for echolocation inshrews. To complement these data, we used a novel behavioural and acoustic approach on two shrewspecies, representative for the two large shrew subfamilies. In both species, experimental manipulationof substrate density affected the number of twittering calls uttered during exploration. Thisadaptation of call rate to habitat clutterdness parallels bat echolocation and suggests that shrews usereverberations of their calls for probing habitat routing or type. The shrew signals were tonal, larynxproduced calls in the sonic range and not ‘echolocation clicks’, as had been suggested by other studies.To test the utility of those calls for orientation, we insonified different natural shrew habitats withan “artificial shrew” (small speaker mounted close to a sensitive microphone). We found that shrewlikecalls indeed yield echo scenes useful for habitat assessment, routing and spatial orientation.O BB.6 (Su) - ENFunctions of complex signalling in Nightingales (Luscinia megarhynchos)Silke KipperAG Verhaltensbiologie, Freie Universität BerlinMany animal species evolved complex communication systems consisting of different signals thatcan be assembled in various sequences and combinations. Birdsong is one of the most prominent andwell-understood examples to study functions of such signalling systems. Hereby, the complexity ofsong in some bird species has been particularly puzzling. I will present recent findings that elucidatefunctions of song type repertoires in the common nightingale (Luscinia megarhynchos). Males of thespecies possess large song type repertoires (mean 190 songs/male) with remarkable inter-individualdifferences in repertoire size and repertoire composition. To investigate repertoire size, I analysedlong sequences of undisturbed nocturnal song bouts of 12 free ranging territorial nightingales resultingin repertoire curves reaching towards saturation (indicating that not many more new song typeswere going to occur). I will show that, owing to specific song delivery rules, a much shorter songsequence is sufficient to reliably predict a bird’s repertoire size. In addition, to address the role ofrepertoire composition, I conducted playback experiments testing reactions to songs individual birdsdid or did not have in their repertoires. Results show that nightingales differed between these twosong qualities, suggesting that the development of a large repertoire is not only a matter of producinghigh versatility, but also allows fine-tuned interactions among males.