Biology subjects

Burkart, J.

Publications and source records attributed to Burkart, J..

3 recordsLinked to original sources

bioRxiv2026

Identity-resolved vocal exchanges in multi-marmoset settings

Acoustic communication is tightly coupled to collective behaviour and social network structure in many animal societies. Yet continuous, identity-resolved recordings of multiple concurrent signalers are challenging. We evaluated a commercial acoustic camera for marmoset (Callithrix jacchus) vocal behavior across controlled bench tests and naturalistic family interactions. Spectral characterization showed the system is closest to neutral and most sensitive in 5-10 kHz, supporting reliable detection without correction in this range. Static localization accuracy was between 1-3 cm across the experimental enclosure. In simultaneous two-source tests, separation depended strongly on geometry and intensity level: very small spacing (20 cm) produced a single merged hotspot, frame-wise co-representation of multiple sources was infrequent and biased by sub-decibel level asymmetries. In natural 15-min family recordings (N=519 calls), the camera detected 96.5% of calls, among detected events, caller assignment was 97.6% correct (overall 94.2%). Ground-truth playback confirmed near-ceiling detection ([~]100%) and high assignment with two emitters ([~]98%), with reduced attribution in crowded four-emitter layouts. Together, these results indicate that acoustic imaging can deliver high detection and accurate caller attribution for typical marmoset vocalizations, with primary limitations arising from spatial crowding and small inter-source level differences. Importantly, this limitation can be mitigated in the native software by sequentially silencing suspected sound sources. The approach thus provides a practical and reliable path toward continuous, identity-resolved vocal monitoring in freely behaving primates.

animal behavior and cognition↗

bioRxiv2024

Common marmosets use body posture as multi-functional signal to solicit, maintain, and modify social play

Social play is a highly active social interaction, characterized by rapid exchanges of various behaviors with multiple partners. Many primates use bodily expressions during social play, yet the potential signaling function of these expressions remains unclear. This study investigated whether common marmosets (Callithrix jacchus) use body posture as signal to regulate play. We recorded play within three captive common marmoset family groups using multiple cameras simultaneously to capture the fast-paced and high frequency behaviors. Three distinct signals (i.e. supine, hide, stalk) and six distinct play types (i.e. wrestle, chase, pounce, touch, catch, pull) were identified. We used a multi-state time-to-event model to analyze the sequences of play, including short-and long-term transitions between different states (i.e. signal, play, or rest/nothing). Our data-driven approach accounted for uncertainty in the duration of play bouts, using probabilistic classification rather than arbitrary bout thresholds. The resulting classifications allowed us to assess the social function of signals by comparing play behavior to a resting state baseline. We found that the presence of a signal: (1) increases the probability to play; (2) extends the duration of play; (3) leads to more diverse play; and (4) increases the probability of play fighting. Marmosets also show turn-taking of signaling and initiating subsequential play. These results show that marmosets use postures as communicative signals to initiate and change play dynamics, and thereby establish a mutual understanding of the joint action. The two-fold contribution of this study concerns novel analytical methods and a deeper conceptual understanding of primate communication. Play and its signals are important elements in the evolution of language, and our research contributes to its further understanding.

animal behavior and cognition↗

bioRxiv2023

Neurodevelopmental timing and socio-cognitive development in a prosocial cooperatively breeding primate (Callithrix jacchus)

Primate, and especially human, brain development is experience-dependent: it is shaped by the inputs received during critical periods. During early development, these inputs systematically differ between independently and cooperatively breeding species, because in cooperative breeders infants are interacting from birth with multiple caretakers and have to thrive in a richer and more challenging social environment. Here, we study the neurodevelopmental timing of the cooperatively breeding common marmoset and how it maps onto behavioral and developmental milestones. To obtain meaningful correlations of structure-function co-constructions, we combine behavioral, imaging (anatomical and functional) and neural tracing experiments. We focus on brain areas that are critically involved when observing conspecifics interacting with others and find that (i) these areas develop in clusters; (ii) these areas reach their maximum gray matter volume shortly after peak provisioning, when immatures are intensely provisioned by group members; (iii) the differentiation of these areas coincides with the period of intense negotiation between immatures and multiple adults over food, the birth of the next set of siblings, and the task of becoming a helper. Moreover, like in humans, differentiation is not fully completed at the age of first reproduction. In sum, we find that the developmental timing of social brain areas coincides with key social and developmental milestones in marmosets, and extends into early adulthood. This rich social input is likely critical for the emergence of the particularly strong prosociality and socio-cognitive skills of marmosets. Since humans are cooperative breeders too, these findings have strong implications for the evolution of human social cognition.

neuroscience↗