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D Todt

Publications and source records attributed to D Todt.

12 recordsLinked to original sources
PubMed1999

Auditory-visual stimulus pairing enhances perceptual learning in a songbird.

In many oscine birds, song learning is affected by social variables, for example the behaviour of a tutor. This implies that both auditory and visual perceptual systems should be involved in the acquisition process. To examine whether and how particular visual stimuli can affect song acquisition, we tested the impact of a tutoring design in which the presentation of auditory stimuli (i.e. species-specific master songs) was paired with a well-defined nonauditory stimulus (i.e. stroboscope light flashes: Strobe regime). The subjects were male hand-reared nightingales, Luscinia megarhynchos. For controls, males were exposed to tutoring without a light stimulus (Control regime). The males' singing recorded 9 months later showed that the Strobe regime had enhanced the acquisition of song patterns. During this treatment birds had acquired more songs than during the Control regime; the observed increase in repertoire size was from 20 to 30% in most cases. Furthermore, the copy quality of imitations acquired during the Strobe regime was better than that of imitations developed from the Control regime, and this was due to a significant increase in the number of 'perfect' song copies. We conclude that these effects were mediated by an intrinsic component (e.g. attention or arousal) which specifically responded to the Strobe regime. Our findings also show that mechanisms of song learning are well prepared to process information from cross-modal perception. Thus, more detailed enquiries into stimulus complexes that are usually referred to as social variables are promising. Copyright 1999 The Association for the Study of Animal Behaviour.

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PubMed1998

Local variation in Barbary macaque shrill barks.

We examined vocalizations of Barbary macaques, Macaca sylvanus, given in response to a dog, in two populations, at Rocamadour, France, and Salem, Germany. Calls were recorded from 16 individuals in Rocamadour and 23 individuals in Salem. Despite an overall similarity, an acoustic analysis revealed significant differences in the call structure between populations. To test the perceptual salience of these acoustic differences, we conducted playback experiments in both populations in which calls from the own or the other population were broadcast. The overall response pattern did not differ significantly between the populations with regard to the origin of the call. However, subjects responded slightly, but significantly longer after playback of calls from the other group. Although call function apparently determined the general response of subjects, they none the less discriminated between calls from different origins. These results suggest a small but possibly meaningful plasticity in call production. Copyright 1998 The Association for the Study of Animal Behaviour.

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PubMed1997

Effects of dyadic vocal interactions on other conspecific receivers in nightingales.

During vocal interactions birds can time their song output so that their songs overlap those of a conspecific. Such overlapping is usually interpreted as a directed signal of arousal or as a signal of readiness to escalate contests. Inevitably, these interactions can often be heard by other conspecifics. To investigate if these conspecifics would perceive and use information derived from listening to others' interactions we conducted playback experiments in the field on male territorial nightingales, Luscinia megarhynchos. We tested whether asymmetric interactions, in which one bird overlaps the song of another individual, influences the behaviour of additional, passive conspecific receivers. To test the influence of song overlapping on a third individual, each subject received one playback treatment in which two intruders were simulated by a dual speaker playback design. Songs broadcast from one loudspeaker overlapped those from the other loudspeaker. Subjects responded more intensely at the side of the overlapper than at the side of the loudspeaker from which the song that was overlapped was broadcast. These differences in response persisted in a second test in which songs of only one of the formerly interacting rivals were played. The results suggest that, even if song overlapping is a signal directed towards the singer whose song is overlapped, this information is perceived and used by additional receivers. Such information on rivals' behaviour during an interaction might help an individual decide which strategies to adopt in possible future interactions with these conspecifics.Copyright 1997 The Association for the Study of Animal Behaviour

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