Abstracts - Deutsche Zoologische Gesellschaft

Behavioral Biology Posters 105P BB.1 - ENHormonal correlates of song seasonality and breeding status in the domesticatedcanary (Serinus canaria)Stefan Leitner, Cornelia VoigtAbteilung Verhaltensneurobiologie, Max-Planck-Institut für Ornithologie, SeewiesenIn most bird species of the temperate zones seasonal events such as breeding are usually associatedwith seasonal fluctuations of steroid hormones that are often regarded as the basis for large-scalechanges in neuroanatomy of brain regions that are involved in the control of reproductive behavioursuch as song. In a long-term study on an aviary population of domesticated canaries, one of the mostwidely used models to study neural correlates of behavioural plasticity, we first found that song parameterssuch as song length and the proportion of non-repeated syllable types changed seasonallybut not annually. In contrast, repertoire size remained constant throughout the seasons, although repertoirecarry-over was lower on a seasonal compared to an annual basis. Further, the breeding seasonrepertoire contained significantly more sexually attractive syllable types than that of the non-breedingseason. These features are likely to be hormone dependent, as during the breeding season maleshad increased plasma levels of testosterone (T) compared to the non-breeding season. In contrast,fluctuations of plasma T in the course of the breeding season had no impact on song structure, suggestingthat there exist a threshold for hormone dependent song changes. The data were consistentwith our results obtained in a wild canary population, but partly in contrast to findings in a differentdomesticated canary strain, which implies caution when performing behaviour-brain relationshipsbetween different strains.P BB.2 - ENLying without blushing? An experimental study on the begging behaviour in Wilson’sStorm-petrel nestlingsAnja Nordt, Hans-Ulrich PeterInstitut für Ökologie, Friedrich-Schiller-Universität JenaWhether parents or their dependent offspring control provisioning and how resource allocation ismediated behaviourally are fundamental questions in the context of parent – offspring conflict. Pronouncedbegging display of nestlings commonly precedes and accompanies provisioning by parentsand is widely seen as advertisement of food demand at the nest. Vocalisations during feeding ofchicks of a small long-lived seabird, the Wilson’s Storm-petrel (Oceanites oceanicus), were recordedon King George Island, maritime Antarctic, to evaluate their information content and effects onregulating provisioning by the attending adult. A supplemental feeding experiment was conducted inorder to verify empirical findings. During the control period chicks signalled their nutritional needadequately. They conveyed information about their body condition through the number and soundfrequency of begging calls uttered during feeding sessions. Parents responded to this information bydelivering larger meals to nestlings in a poorer state but within a certain range under the constraintsof food availability.Data suggest that parents used classic as well as sonagraphic components of thebegging display to adjust provisioning rates. The feeding frequency was based on the number oflong calls of the last begging session, while the meal size depended on sonagraphic parameters, e.g.syllable duration and pitch of calls uttered during the prevailing feeding.