Number of syllables in cuckoo Cuculus canorus calls: A test using a citizen science project

Piotr Tryjanowski,Federico Morelli,Karolina Slezak,Anders Pape Møller,Yanina Benedetti

doi:10.1038/s41598-018-31329-1

Abstract

Recent studies revealed that the call of the common cuckoo Cuculus canorus has more inter-individual than intra-individual variation and that the number of syllables depends on environmental conditions, but also the presence of male and female conspecifics. However, still very little is known about how song varies at a global scale, especially considering the wide distribution of this species across most of Europe and Asia. Xeno-canto.org is a vocalization repository for birdsong. We used xeno-canto.org as a data source for investigating the variables that affect the number of syllables in cuckoo calls at a large spatial scale. At a very broad geographical scale, the number of syllables in cuckoo calls predicted bird species richness. Additionally, female calls were associated with shorter males calls, and there was a positive correlation between the interaction between female calls and the number of host races parasitized by the cuckoo. These findings confirm that intraspecific and interspecific interactions significantly affect the number of syllables in cuckoo calls, and both environmental variables and biotic interactions should be considered in future studies of vocalizations in cuckoos. Last but not least, we demonstrated that a citizen science project is a useful source for ecological studies at large spatial scales.

Highlights

The common cuckoo Cuculus canorus has fascinated humans since millennia[1]
The objectives of this study were to use a dedicated media and citizen science sources to explore at a wider spatial scale (1) the factors that influence the number of syllables in cuckoo calls, (2) whether the number of syllables of cuckoo calls reflects bird species richness, and (3) if cuckoo call activity is determined by environmental factors
The opportunity for access to a huge amount of data from social media and citizen science projects is changing the way in which scientific studies and analyses of biological records are performed

Summary

Introduction

The common cuckoo Cuculus canorus ( cuckoo) has fascinated humans since millennia[1]. The occurrence of cuckoos reflects overall species richness of their hosts. For this reason, the cuckoo has recently been suggested to reliably indicate biodiversity[7,8,9]. Collection of data at continental and global scales produces hundreds of millions of observations of thousands of species every year[20]. The objectives of this study were to use a dedicated media and citizen science sources to explore at a wider spatial scale (1) the factors that influence the number of syllables in cuckoo calls, (2) whether the number of syllables of cuckoo calls reflects bird species richness, and (3) if cuckoo call activity is determined by environmental factors. We discuss how dedicated media sources can provide useful scientific data and thereby contribute to ecology and conservation

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Conclusion