Illuminating the nightlife of two Neotropical nightjars: vocal behavior over a year and monitoring recommendations

Abstract

The ecology of tropical wildlife remains unknown for most nocturnal species owing to difficulties in performing night surveys. To improve our understanding of the ecology of nocturnal tropical birds, we monitored the calling activity of two Neotropical nightjars, the Little nightjar (Setopagis parvula) and the Common pauraque (Nyctidromus albicollis), over an annual cycle at four sites in the Brazilian Pantanal. The calling activity of both species was restricted to the nocturnal period and showed peaks of activity just before dawn and just after dusk. The Little nightjar was detected from early June to late January owing to the migratory habits of the species, while the Pauraque was detected throughout the year. Our results suggest that the breeding season of both species starts in August, and the nesting phase probably takes place in September at the end of the dry season. This might be related to the typical increase in arthropod abundance after the first rains in tropical habitats with seasonal rainfall. Future surveys of these species should be performed in the last fortnight of August at 5 am, a period during which the calling activity of both nightjars was maximum. Autonomous sound recorders should be left in the field for a minimum of 9 days to record a reliable vocal activity rate. Acoustic monitoring, coupled with automated signal recognition, has proven to be a useful tool for monitoring tropical nightjars and may be useful to increase our knowledge about the ecology of other nocturnal tropical species.

KEY WORDS:

• acoustic monitoring
• Brazil
• Caprimulgiformes
• Nyctidromus
• Pantanal
• Setopagis
• autonomous sound recorder

Acknowledgments

We thank the SESC Pantanal, Mato Grosso, for permission to conduct research on their property and their logistical help with our fieldwork. This study is part of the biodiversity monitoring project Sounds of the Pantanal–The Pantanal Automated Acoustic Biodiversity Monitoring of INAU, Cuiabá, Mato Grosso, Brazil, which was conducted under SISBIO permit no. 39095 (K.-L. Schuchmann). We are grateful to three anonymous reviewers for their helpful comments to improve the manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.

Author contribution

1. Conceived the idea, design, experiment (supervised research, formulated question or hypothesis): C. Pérez-Granados, K.-L. Schuchmann. 2. Performed the experiments (collected data, conducted the research): K.-L. Schuchmann. 3. Wrote the paper (or substantially edited the paper): C. Pérez-Granados, K.-L. Schuchmann. 4. Developed or designed methods: C. Pérez-Granados. 5. Analyzed the data: C. Pérez-Granados. 6. Contributed substantial materials, resources, or funding: K.-L. Schuchmann.

Data accessibility

The data used in this study are archived on Figshare repository and can be accessed at: https://doi.org/10.6084/m9.figshare.11478330.v1

Supplementary material

Supplemental data for this article can be accessed at https://doi.org/10.1080/03949370.2020.1753117.

Additional information

Funding

We greatly appreciate the financial support from the following institutions: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior–Brasil (CAPES)-Finance Code 01; Instituto Nacional de Ciência e Tecnologia em Áreas Úmidas (INAU/UFMT/CNPq); Centro de Pesquisa do Pantanal (CPP); and Brehm Funds for International Bird Conservation (BF), Bonn, Germany