Biology subjects

Petruskova, T.

Publications and source records attributed to Petruskova, T..

5 recordsLinked to original sources

bioRxiv2026

Global patterns and evolution of avian song complexity

Why birds evolved complex songs has been a long-standing puzzle. Here, by quantifying song complexity in 4,940 species (83% of all passerines), we show a latitudinal gradient in song complexity, with the most complex songs occurring in temperate, open-habitat bird assemblages characterized by relatively inconspicuous plumage. Using comparative analyses controlled for common ancestry, we find little support for traditional explanations based on sexual selection intensity, intelligence signaling, or species richness. Instead, complex songs evolve primarily in song-learning passerines, especially migrants, habitat generalists, and species breeding in open habitats where structured acoustic signals transmit more efficiently. Together, our findings indicate that global variation in song complexity emerges from the interaction between vocal learning, ecological context, and evolutionary history rather than from a single selective driver.

evolutionary biology↗

bioRxiv2025

Unique rhythmic signatures in arrhythmic birdsong

Animal rhythms are gaining increasing attention in the studies of behaviour and musicology. Recently, it has been shown that rhythm itself can be used as an information coding channel. Now we ask: does this hold true for arrhythmic sequences? To answer that, we analysed songs of the tawny pipits (Anthus campestris), migratory songbirds known for their simple songs. Using focal recordings of 384 individuals from six populations collected across their European breeding range, we calculated an extensive set of rhythmic and temporal indices to describe each song. First, the pattern of these songs was inspected and shown to be arrhythmic. Second, songs belonging to specific individuals and populations were compared using permuted discriminant function analysis and supervised uniform manifold approximation and projection. To describe the level of individuality of the rhythmic structure alone, we calculated Beechers statistic for all songs, as well as the potential of identity coding for each parameter separately. We show that tawny pipit males sing using individual rhythmic patterns in their arrhythmic songs, and that modern rhythmic indices, such as beat precision and integer ratios, are among some of the most individually distinct parameters of their songs. Furthermore, contrary to previous investigations based on the spectral shape and basic frequency and temporal characteristics of these songs, we show that the species displays population-specific temporal patterns, with significant differences throughout its European range. This study is the first to demonstrate geographic scale differences in birdsong rhythm, and to show that rhythmic analysis can provide useful descriptions of arrhythmic sequences.

animal behavior and cognition↗

bioRxiv2025

Assessing the Effective Range for Individual Acoustic Identification: Comparison of Manual and Automatic Methods

Individual Acoustic Monitoring (IAM), especially when combined with passive acoustic monitoring (PAM), offers a non-invasive alternative to traditional mark-recapture methods to gain insights into species demography. Few studies have examined how identification decreases over distance along with degradation of identity cues. In this study, we conducted a song transmission experiment to quantify the range at which individual Yellowhammers (Emberiza citrinella) can be reliably identified. Songs from ten males (20 songs per individual, covering their full repertoire) were broadcast and re-recorded along a 200 m transect using AudioMoth recorders. Comparing manual classification by human observers with BirdNET classifier adapted for individual identification, we assess how well individuals could be distinguished at increasing distances. Humans were confident in assigning identity to a larger proportion of songs. Where identity has been assigned, both human and BirdNET were highly reliable at short distances (up to 50 m) discriminating even between very similar song types shared among males. At moderate distances (100 - 150 m), simple augmentation boosted BirdNETs performance remarkably, almost matching human classification accuracy. Our results indicate that individual recognition remains reliable up to 100 meters where both accuracy and agreement between assignment methods were high. Our results confirm that automated systems offer promising tools for large-scale, non-invasive individual monitoring, but challenges in accuracy and robustness persist at greater distances. We highlight the difference between signal detectability and individual identification range (much shorter) and its importance for optimizing PAM array designs.

zoology↗

bioRxiv2025

Yellowhammer (Emberiza citrinella) males sing using individual isochronous rhythms and maximise rhythmic dissimilarity with neighbours

The temporal structure of an animals vocal output can be cognitively controlled, presenting an interesting aspect for vocal learning species that benefit from diversification. Although birdsong is the most thoroughly studied aspect of animal communication, its rhythms remain largely unknown. Here, we revisit the question of vocal individuality in the songs of male yellowhammers (Emberiza citrinella) purely from a rhythmic perspective. Yellowhammers use simple songs composed of two phrases: the initial phrase, with one individual usually having a repertoire of on average two such phrase types, and the dialect phrase containing the dialect that is the same for all males at a given locality. Some of the initial phrases are commonly shared between various males, but their combinations and frequency contours are individually unique and temporally stable. Using focal recordings of 38 known individuals, collected over three years in the same geographic location, we calculated a set of nine temporal indices to describe each song and compared individuals in a permuted discriminant function analysis. Subsequently, we calculated the potential for individual coding for each of these parameters. To assess whether rhythmic similarity may depend on the singers proximity, we calculated vocal dissimilarity as the Euclidean distances between each two males, and used Kendalls correlation. We show that yellowhammer males use individual rhythms, maintained over different phrase types and carried mostly in the inter-onset-interval variability and syllable rate, as in syllables per second, within the song. There were particularly strong rhythmic differences between singers among the closest neighbours, which decreased over the first 600 m. There was no pattern for neighbours beyond this distance. This study is the first to demonstrate the existence of strong individuality based purely on rhythm, as well as rhythmic differentiation from neighbours, in a songbird. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=52 SRC="FIGDIR/small/660106v1_ufig1.gif" ALT="Figure 1"> View larger version (11K): org.highwire.dtl.DTLVardef@1727ccorg.highwire.dtl.DTLVardef@35cb5borg.highwire.dtl.DTLVardef@1b9db10org.highwire.dtl.DTLVardef@dd1f4d_HPS_FORMAT_FIGEXP M_FIG C_FIG

animal behavior and cognition↗

bioRxiv2020

A global analysis of song frequency in passerines provides no support for the acoustic adaptation hypothesis but suggests a role for sexual selection

Many animals use acoustic signals for communication, implying that the properties of these signals can be under strong selection. The acoustic adaptation hypothesis predicts that species living in dense habitats emit lower-frequency sounds than those in open areas, because low-frequency sounds generally propagate further in denser vegetation. Signal frequency may also be under sexual selection, because it correlates with body size and lower-frequency sounds are perceived as more intimidating. Here, we evaluate these hypotheses by analysing variation in peak song frequency across 5,085 passerine species (Passeriformes). A phylogenetically-informed analysis revealed that song frequency decreases with increasing body mass and with male-biased sexual size dimorphism. However, we found no support for the predicted relationship between frequency and habitat. Our results suggest that the global variation in passerine song frequency is mostly driven by natural and sexual selection causing evolutionary shifts in body size rather than by habitat-related selection on sound propagation. Statement of authorshipTA and PM conceived and designed the study with input from all authors. TA and BK coordinated the study. PM collected the song data. MV performed the statistical analyses with input from WF. MB made the figures with help from MV and PM. TP and HB provided bioacoustic expertise. PM drafted the first version of the manuscript. TA, BK and PM revised and finalized the manuscript with input from all authors. Data availability statementThe data used in this study were collected from publicly available databases. All data and computer code used to generate the results, as well as supplementary figures and tables will be freely available at https://osf.io/fa9ky/.

evolutionary biology↗