Differential effects of anthropogenic noise and vegetation cover on the breeding phenology and success of two urban passerines

The urban environment is associated with a multitude of challenges and stressors for populations of wild species from the surrounding natural environment. Among those, habitat fragmentation and noise pollution are suspected to have negative effects on the behavior and physiology of free-living birds in urban areas. Exposure in early life and chronic exposure to anthropogenic noise could be particularly deleterious, with short-and long-term consequences. In this study, we investigated if noise levels in city parks affect the distribution and reproductive success of two common bird species in the urban environment, the great tit (Parus major) and the blue tit (Cyanistes caeruleus) and if vegetation cover could mitigate those effects. We predicted that high noise levels might correlate with a decreased nest-box occupancy rate, a delayed laying date or a decreased clutch size, hatching, and fledging success. On the contrary, vegetation cover was expected to correlate positively with nest occupancy rate, advanced laying date, increased clutch size, hatching, and fledging success. We used data from population monitoring collected between 2012 and 2019 in parks and green public spaces in the city center and suburbs of Paris, France, and did not find any correlation between nest occupancy rates and noise levels or vegetation cover for both species. Laying date was not significantly related to anthropogenic noise in any species but was delayed with increasing vegetation cover in the great tit, while we did not find any association with clutch size. Hatching success in blue tits negatively correlated with increasing noise levels, and positively with increasing vegetation coverage. Finally, we did not find any correlation between anthropogenic noise or vegetation cover and the clutch size or fledging success in both species. In this study, two closely related species that share a common environment show a different sensibility to environmental parameters during reproduction, a key period for population maintenance. It also highlights the importance of considering multiple parameters when studying wild populations living in the urban environment

Effect of acoustic cue modifications on evoked vocal response to calls in zebra finches (Taeniopygia guttata).

International audienceBesides their song, which is usually a functionally well-defined communication signal with an elaborate acoustic structure, songbirds also produce a variety of shorter vocalizations named calls. While a considerable amount of work has focused on information coding in songs, little is known about how calls' acoustic structure supports communication processes. Because male and female zebra finches use calls during most of their interactions and answer to conspecific calls without visual contact, we aimed at identifying which calls' acoustic cues are necessary to elicit a vocal response. Using synthetic zebra finch calls, we examined evoked vocal response of male and female zebra finches to modified versions of the distance calls. Our results show that the vocal response of zebra finches to female calls requires the full harmonic structure of the call, whereas the frequency downsweep of male calls is necessary to evoke a vocal response. It is likely that both female and male calls require matching a similar frequency bandwidth to trigger a response in conspecific individuals

La reconnaissance vocale au sein du couple chez le Diamant mandarin ( approches neuro-éthologique et biophotonique)

Ce travail de thèse participe à la compréhension des bases comportementales et des mécanismes neurophysiologiques de la reconnaissance vocale au sein du couple mâle-femelle chez le Diamant mandarin Taeniopygia guttata. Par une approche pluridisciplinaire, j'appréhende conjointement les mécanismes de codage-décodage des informations portées par les cris du Diamant mandarin et leurs supports neurobiologiques. Cette démarche a nécessité d'associer des techniques de suivi de l'activité cérébrale aux méthodes de la bioacoustique. Au terme de l'étude, les bases acoustiques et comportementales des reconnaissances spécifique et individuelle liées aux cris ont commencé d'être identifiées. L'influence du contexte social sur la réponse aux cris a notamment été mise en évidence. Des éléments sur les supports cérébraux des reconnaissances spécifiques et individuelles sont également fournis d'une part grâce à la mise en œuvre d'approches classiques telles que le suivi par immunocytochimie post-mortem de l'expression activité-dépendante de " gènes à expression précoce ", et d'autre part grâce à une nouvelle méthode de spectroscopie proche infra-rouge (NIRS : near infra-red spectroscopy) permettant le suivi in-vivo non invasif et en temps réel de l'activité cérébrale lors du traitement neuro-sensoriel des vocalisationsThis work participates in the understanding of the behavioural and neurophysiological basis of vocal recognition between male and female of a pairbond in the zebra finch Taeniopygia guttata. Using a pluridisciplinary approach, this work deals with coding-decoding processes of call-based information and with the associated neurobiological supports. It has needed to associate techniques of cerebral activity probing with methods of bioacoustics. Acoustic and behavioural basis of call-based species-specific and individual recognition have begun to be identified. The influence of social context on the response to call play-back has been demonstrated. Some aspects about the cerebral support of species-specific and individual recognition are provided using, one on hand, classical post-mortem immunocytochemical probing of activity-dependant expression of immediate-early-genes and, the other hand, a new near infra-red spectroscopy (NIRS) method allowing the in-vivo non invasive and real-time monitoring of cerebral activity during neuro-sensory processing of vocalizationsST ETIENNE-BU Sciences (422182103) / SudocSudocFranceF

Social context modulates behavioural and brain immediate early gene responses to sound in male songbird.

International audienceAlthough it is well known that brain sensory information processing is a highly modulated phenomenon, how this brain function is shaped by experience and social context remains a question to explore. In this paper, we present the first attempt to investigate this problem using a songbird acoustic communication paradigm. Social context is well known to influence acoustic communicating behaviours in birds. The present paper investigates whether brain processing of auditory inputs can be modulated by this 'audience effect'. Given that call-based communication is known to be highly context-dependent, we focused on the response of male zebra finches (Taeniopygia guttata) to female calls. We tested to see if the current social context surrounding the hearing bird can modify a sound-induced immediate early gene (IEG) activation in the specific region of the caudomedial nidopallium (NCM), a songbird brain analogous to the superficial layers of the mammalian primary auditory cortex. Our results show that the expression of the sound-induced immediate early gene ZENK in the NCM is considerably enhanced when the hearing bird is in the presence of conspecifics, compared to when he is alone. This context-dependent increase of a sound-induced immediate early gene expression can be correlated with the differential behavioural response of males to the playback of the same acoustic stimulus as a function of social context

Introduction

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Mate recognition by female zebra finch: Analysis of individuality in male call and first investigations on female decoding process.

International audienceZebra finches are monogamous birds living in large assemblies, which represent a source of confusion for recognition between mates. Because the members of a pair use distance calls to remain in contact, call-based mate recognition is highly probable in this species. Whereas it had been previously demonstrated in males [Vignal, C., Mathevon, N., Mottin, S., 2004. Audience drives male songbird response to mate's voice. Nature 430, 448–451], call-based mate recognition remained to be shown in females. By analysing the acoustic structure of male calls, we investigated the existence of an individual signature and identified the involved acoustic cues. We tested to see if females can identify their mates on the basis of their calls alone, and performed preliminary experiments using modified signals to investigate the acoustic basis of this recognition. Playback tests carried on six individuals showed that a female zebra finch is able to perform the call-based recognition of its mate. Our experiments suggested that the female uses both the energy spectrum and the frequency modulation of the male signal. More experiments are now needed to decipher precisely which acoustic cues are used by females for recognition

Introduction

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Introduction

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Impact of group size and social composition on group vocal activity and acoustic network in a social songbird

International audienceIn social species individuals living in the same group may synchronize activities such as movements, foraging or antipredator vigilance. Synchronization of activities can also be observed between partners especially during breeding and can be crucial for breeding success. Vocalizations are behaviours that can be coordinated between individuals, but simultaneous vocalizations in groups have mostly been considered as noise that does not bear any information. Indeed, little is known about the structure and function of vocal communications involving a network of individuals. How individual vocal activity forms part of the communal sound and how the group influences individual vocal activity are questions that remain to be studied. Zebra finches, Taeniopygia guttata, are social, monogamous songbirds that form lifelong pair bonds. In the wild, they are typically found in small groups, with the pair as the primary social unit, and they gather in ‘social’ trees where both females and males produce vocalizations. Here we investigated in the laboratory the influence of group size and composition on general vocal activity and synchrony, as well as the influence of pair bond and spatial location on the finer characteristics of dyads' vocal interactions. We used a set-up that locked the birds at fixed spatial positions of our choosing to control the proximity network and allowed us to match most of the vocalizations with specific in- dividuals. We used an in-house software suite that automatically detects vocalizations from hours of passive recording. We found that zebra finch groups synchronized their general vocal activity with waves of collective vocalizations, which depended on both the size and the composition of the group. The acoustic network was shaped by pair bonds at different timescales. Birds preferentially vocalized close in time to (synchrony) or directly after (turn taking) their partner when it was present and the nearest neighbour when the partner was not available