Song structure and syllable and song repertoires of the Saffron Finch (Sicalis flaveola pelzelni) breeding in Argentinean pampas

Artificial Light at Night Drives Earlier Singing in a Neotropical Bird

Simple Summary

Urban birds have to cope with dominant stressors as anthropogenic noise and artificial light at night by adjusting their song traits. However, evidence of such adjustments has been studied thus far in temperate cities, rather than tropical cities. Here, I tested whether noise and light pollution influence earlier singing behavior in a tropical bird, the Saffron Finch. Birds in highly urbanized sites sang earlier at dawn and this timing difference was driven by light pollution instead of anthropogenic noise. Overall, these results suggest that light pollution could have a detrimental impact on the circadian rhythms of urban tropical birds such as daily singing routines.

Abstract

Anthropogenic noise and artificial light at night (ALAN) can disrupt the morning singing routines of urban birds, however, its influence on tropical species remains poorly explored. Here, I assessed the association between light and noise pollution with the dawn chorus onset of the Saffron Finch (Sicalis flaveola) in a city in Colombia. I studied 32 sites comprised of different conditions of urban development based on built cover. I recorded the time of the first song of the Saffron Finch, the conspecific density and measured anthropogenic noise and ALAN using smartphone apps. The findings of this study show that Saffron Finches living in highly developed sites sang earlier at dawn than those occupying less urbanized sites. Unexpectedly, this timing difference was related to ALAN instead of anthropogenic noise, suggesting that light pollution could drive earlier dawn chorus in a tropical urban bird. Saffron Finches could take advantage of earlier singing for signaling territorial ownership among neighbors. Future studies need to assess the influence of ALAN on the dawn chorus timing of Neotropical urban birds.

Sequential organization of birdsong: relationships with individual quality and fitness

Many vocalizing animals produce the discrete elements of their acoustic signals in a specific sequential order, but we know little about the biological relevance of this ordering. For that, we must characterize the degree by which individuals differ in how they organize their signals sequentially and relate these differences to variation in quality and fitness. In this study, we fulfilled these tasks in male collared flycatchers (Ficedula albicollis). We characterized the sequential order of syllables with a network analysis approach and studied the consistency of network variables on distinct time scales (within day, between days, and between years), and assessed their relationship with such quality indicators like age, body condition, arrival date, and fitness related proxies like survival to the next year and pairing success. We found that the syllables were associated nonrandomly with one another and both the frequency differences of consecutive syllables and the number of motif types were higher in the original than in randomized syllable sequences. Average degree and small-worldness showed considerable among-individual differences and decreasing repeatability with increasing time scale. Furthermore, we found relationships between male age and average degree among and within individuals. Accordingly, older males produce syllable sequences by using common syllables less often than younger individuals. However, the network variables showed no relationship with fitness-related variables. In conclusion, the sequential organization of birdsong has the potential to encode individual-specific characteristics, which thus could be used as signal in social interactions and thus potentially could be subject to sexual selection.

Impacts of noise pollution on the agonistic interactions of the saffron finch (Sicalis flaveola Linnaeus, 1766)

Impacts of noise pollution are recognized as a source of stress for animals and as a form of environmental degradation. Behavioural changes associated with noise, such as reduction of reproductive success, reduction in feeding behaviour, increase in vigilance behaviours and inability to detect environment acoustic signals, are observed. The aim of the present study was to evaluate how noise influences aggressive behaviour of the saffron finch (Sicalis flaveola). We conducted tests of territoriality-aggressiveness against conspecifics. Seven individuals were tested, with six tests per individual being conducted in two treatments (traffic pollution and ambient noise), totalling 84 tests. The noise treatment significantly altered the agonistic interactions of the saffron finches, with territorial males exhibiting less aggressive behaviours towards intruders.

Genetic mating system, population genetics and effective size of Saffron Finches breeding in southern South America

Thraupidae (Tanagers and allies) show a remarkable array of behaviors, ecologies, morphologies and plumage colors, offering a great opportunity to investigate the evolution of avian mating strategies. We characterize the population genetics and mating system of Sicalis flaveola pelzelni, a socially monogamous Neotropical songbird with biparental care. We found moderate to high levels of neutral genetic variation, similar across three breeding seasons, consistent with large and stable populations, and no temporal genetic structure. Parentage analyses of 114 adults and 198 nestlings (54 nests) revealed 31.8% of extra-pair offspring (EPO) and 51.8% of broods with at least one extra-pair chick. Extra-pair paternity (EPP) rates varied across seasons and were significantly higher in 2014/2015. Neither breeding synchrony nor pair genetic relatedness was significantly associated to EPP rates. Males paired with females in nests with and without EPO were equally heterozygous, and EPO were significantly less heterozygous than within-pair offspring, not supporting the 'indirect genetic benefits' hypotheses. Females were more related to their extra-pair mates than to their social mates, not supporting the 'inbreeding avoidance' hypothesis. The non-monogamous genetic mating system uncovered here seems not to lower the effective size of the population, which was higher than the sample size of adult breeders. We report and discuss possible cases of quasi-parasitism, as indicated by maternity exclusion patterns. We contribute novel information to expand the knowledge about the largely unexplored genetic mating systems of Thraupidae. Our findings also set the stage for further studies examining if plumage coloration or song traits predict paternity gain or loss in Saffron Finches.