Sympatric finches differ in visitation patterns to watering holes: implications for site-focused bird counts

ABSTRACT

Estimating trends in population size is critical for understanding population status and assessing the success of management interventions. Visual counts of birds as they congregate around predictable locations, such as waterholes, is a popular technique for estimating population size. Bird counts are used as a proxy for abundance, but how the relationship between counts and actual abundance varies over space and time is rarely assessed. Here, we demonstrate that colour banding and motion detection cameras provided a good method for monitoring finch visitation patterns across space and time. These methods were validated using three sympatric finch species, the abundance of which have been estimated from waterhole counts over many years. The study showed significant temporal inter-species variability in the proportion of birds visiting waterholes and the number of times the same individual returned to the same waterhole during the early morning. Bird visitation rates also varied between consecutive days, across adjacent waterholes and at different stages of the dry season. Our study suggests that spatiotemporal variation in individual behaviour may introduce substantial error into site-focused bird counts and we recommend considering this in census design.

KEYWORDS:

• Gouldian Finch
• Long-tailed Finch
• Masked Finch
• waterhole counts
• camera trap
• colour banding

Acknowledgements

We thank the Balanggarra Aboriginal Corporation for access to their native title land and other landowners who allowed us access to the study sites so that this research could take place. We are also thankful for field assistance from Mark Conboy, David Loewensteiner, Paul Bardens, Sarah Smith and additional training provided by Jan Lewis and John Rawsthorne. We also thank Jeremy Garnett of Top End Editing for proofreading.

Author contributions

S.J.C.: Roles – Conceptualisation, Formal analysis, Data curation, Investigation, Methodology; Writing – original draft, review, & editing. T.L.C.: Roles – Conceptualisation, Formal analysis, Data curation, Investigation, Methodology; Writing – review. I.J.R.: Roles – Conceptualisation, Methodology, Supervision; Writing – review. S.T.G.: Roles – Conceptualisation, Supervision; Writing – review. H.A.C.: Roles – Conceptualisation; Funding acquisition; Investigation; Methodology; Resources; Supervision; Writing – original draft & review.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed at https://doi.org/10.1080/01584197.2022.2104734.

Additional information

Funding

The research was funded by an Australian Research Council [LP1601101716] grant, with Save the Gouldian Fund, Western Australia Department of Biodiversity, Conservation and Attractions, and WWF-Australia as linkage partners. Charles Darwin University provided additional support and S.J.C. was also supported by the Australian Government Research Training Program Stipend Scholarship. This study was undertaken under scientific permits from the Western Australian Department of Parks and Wildlife (permit No. 08-001715-2), Western Australian Department of Biodiversity Conservation and Attractions (permit No. FO25000021), Parks and Wildlife Commission of the Northern Territory (permit No. 61442), the Australian Bird and Bat Banding Scheme (project no. 545–9), and the Charles Darwin University Animal Ethics Committee (AEC no. A17015).