Life-history and hormonal control of aggression in black redstarts: blocking testosterone does not decrease territorial aggression, but changes the emphasis of vocal behaviours during simulated territorial intrusions

Introduction: Many studies in behavioural endocrinology attempt to link territorial aggression with testosterone, but the exact relationship between testosterone and territorial behaviour is still unclear and may depend on the ecology of a species. The degree to which testosterone facilitates territorial behaviour is particularly little understood in species that defend territories during breeding and outside the breeding season, when plasma levels of testosterone are low. Here we suggest that species that defend territories in contexts other than reproduction may have lost the direct regulation of territorial behaviour by androgens even during the breeding season. In such species, only those components of breeding territoriality that function simultaneously as sexually selected signals may be under control of sex steroids.<p></p> Results: We investigated black redstarts (Phoenicurus ochruros), a species that shows periods of territoriality within and outside of the breeding season. We treated territorial males with an anti-androgen and an aromatase inhibitor during the breeding season to block both the direct and indirect effects of testosterone. Three and ten days after the treatment, implanted males were challenged with a simulated territorial intrusion. The treatment did not reduce the overall territorial response, but it changed the emphasis of territoriality: experimental males invested more in behaviours addressed directly towards the intruder, whereas placebo-treated males put most effort into their vocal response, a component of territoriality that may be primarily directed towards their mating partner rather than the male opponent.<p></p> Conclusions: In combination with previous findings, these data suggest that overall territoriality may be decoupled from testosterone in male black redstarts. However, high levels of testosterone during breeding may facilitate-context dependent changes in song

Testosterone affects song modulation during simulated territorial intrusions in male black redstarts (Phoenicurus ochruros)

Although it has been suggested that testosterone plays an important role in resource allocation for competitive behavior, details of the interplay between testosterone, territorial aggression and signal plasticity are largely unknown. Therefore, we investigated if testosterone acts specifically on signals that communicate the motivation or ability of individuals to engage in competitive situations in a natural context. We studied the black redstart, a territorial songbird species, during two different life-cycle stages, the early breeding phase in spring and the non-breeding phase in fall. Male territory holders were implanted with the androgen receptor blocker flutamide (Flut) and the aromatase inhibitor letrozole (Let) to inhibit the action of testosterone and its estrogenic metabolites. Controls received a placebo treatment. Three days after implantation birds were challenged with a simulated territorial intrusion (STI). Song was recorded before, during and after the challenge. In spring, both treatment groups increased the number of elements sung in parts of their song in response to the STI. However, Flut/Let-implanted males reacted to the STI with a decreased maximum acoustic frequency of one song part, while placebo-implanted males did not. Instead, placebo-implanted males sang the atonal part of their song with a broader frequency range. Furthermore, placebo-, but not Flut/Let-implanted males, sang shorter songs with shorter pauses between parts in the STIs. During simulated intrusions in fall, when testosterone levels are naturally low in this species, males of both treatment groups sang similar to Flut/Let-implanted males during breeding. The results suggest that song sung during a territorial encounter is of higher competitive value than song sung in an undisturbed situation and may, therefore, convey information about the motivation or quality of the territory holder. We conclude that testosterone facilitates context-dependent changes in song structures that may be honest signals of male quality in black redstarts

Optimierung und Standardisierung des Absatzprognose-Prozesses für den Vertriebskanal Original Equipment Services des Automotive Aftermarkets der Robert Bosch GmbH in der Vertriebsregion Europa

Diese Bachelor Thesis befasst sich mit dem Prozess der Erstellung von Absatzprognosen für den Vertriebskanal Original Equipment Services des Automotive Aftermarkets der Robert Bosch GmbH in der Vertriebsregion Europa. Die Bedarfsplanung im Ersatzteilmarkt ist durch zwei unternehmerische Ziele geprägt, die nur schwer zu vereinen sind: Die Erreichung eines optimalen Service Levels und die Reduzierung der Bestandskosten auf ein Minimum. Um diesen beiden Zielen gerecht zu werden und dem Kunden die benötigen Ersatzteile so schnell wie möglich zur Verfügung stellen zu können, werden Prognosen eingesetzt. Es gibt verschiedene Prognoseverfahren, die alle dazu dienen die zukünftigen Absatzmengen so genau wie möglich vorherzusagen. Anhand von Interviews, Schulungsunterlagen, internen Dokumenten sowie Kennzahlen wird der Zustand des Prognoseprozesses ermittelt. Durch die Ist-Analyse sowie die Durchführung eines internen Benchmarkings mit zwei weiteren Vertriebskanälen, werden Optimierungspotentiale am derzeitigen Prognoseprozess aufgedeckt und erläutert. Ziel dieser Arbeit ist es auf Basis der gewonnenen Erkenntnisse einen standardisierten und optimierten Prognoseprozess zu ermitteln, der zu einer Verbesserung der Planungsgüte, der Kundenzufriedenheit und der Bestandssituation führt

Buzzwords in females' ears? The use of buzz songs in the communication of nightingales (Luscinia megarhynchos).

Differences in individual male birds' singing may serve as honest indicators of male quality in male-male competition and female mate choice. This has been shown e.g. for overall song output and repertoire size in many bird species. More recently, differences in structural song characteristics such as the performance of physically challenging song components were analysed in this regard. Here we show that buzz elements in the song of nightingales (Luscinia megarhynchos) hold the potential to serve as indicators of male quality and may therefore serve a communicative function. Buzzes were produced with considerable differences between males. The body weight of the males was correlated with one measure of these buzzes, namely the repetition rate of the buzz subunits, and individuals with larger repertoires sang buzzes at higher subunit-rates. A model of buzz performance constraints suggested that buzzes were sung with different proficiencies. In playback experiments, female nightingales showed more active behaviour when hearing buzz songs. The results support the idea that performance differences in the acoustic fine structure of song components are used in the communication of a large repertoire species such as the nightingale

Does age matter in song bird vocal interactions? Results from interactive playback experiments

<p>Abstract</p> <p>The song of oscines provides an extensively studied model of age-dependent behaviour changes. Male and female receivers might use song characteristics to obtain information about the age of a signaller, which is often related to its quality. Whereas most of the age-dependent song changes have been studied in solo singing, the role of age in vocal interactions is less well understood. We addressed this issue in a playback study with common nightingales (<it>Luscinia megarhynchos</it>). Previous studies showed that male nightingales had smaller repertoires in their first year than older males and males adjusted their repertoire towards the most common songs in the breeding population. We now compared vocal interaction patterns in a playback study in 12 one year old and 12 older nightingales (cross-sectional approach). Five of these males were tested both in their first and second breeding season (longitudinal approach). Song duration and latency to respond did not differ between males of different ages in either approach. In the cross-sectional approach, one year old nightingales matched song types twice as often as did older birds. Similarly, in the longitudinal approach all except one bird reduced the number of song type matches in their second season. Individuals tended to overlap songs at higher rates in their second breeding season than in their first. The higher levels of song type matches in the first year and song overlapping by birds in their second year suggest that these are communicative strategies to establish relationships with competing males and/or choosy females.</p

Model of buzz constraints.

<p>Buzz rate, mean frequency and duration of 157 buzzes produced by 15 individuals. The surface shows the upper bound regression calculated by a subset of these data (see methods). Vertical lines reflect the distance of the actual buzz duration to the length predicted by the upper bound regression (residuals of duration to the upper bound regression). The 15 birds are clustered according to their repertoire size in three classes (open circles = birds with small repertoires (<150 song types, n = 3). Filled circles = birds with medium size repertoires (n = 7) and filled triangles = birds with large repertoires (>180 song types, n = 5). See text for further explanations.</p

Playback experiment.

<p>Responses of six female nightingales to playbacks containing or not containing buzz songs. <b>A</b> the number of location changes and <b>B</b> the number of tail lifts the females performed during the playbacks. For both responses, exact paired Wilcoxon signed rank test, p<0.05.</p