Season and sugar concentration affect bird behaviour at urban sugar-water feeders

ABSTRACT

Sugar-water bird feeding in residential backyards is increasingly popular, but its effects on wildlife are poorly understood. One concern is whether it results in maladaptive behaviour, such as reliance on artificial food or increased aggression due to increased density of visiting individuals. We studied sugar-water feeder-associated bird behaviour in two cities with different climates. We investigate whether season, city, or sugar concentration influenced bird foraging activity and aggressiveness. We then test whether feeder presence affected backyard bird composition. Birds were most aggressive and used sugar-water feeders most actively in winter, especially the omnivorous native tauhou (Zosterops lateralis). We also found city and seasonal differences in sugar-water feeder usage and aggression. Further, in Auckland, the city with the warmer climate, New Zealand’s largest nectarivorous species, tūī (Prosthemadera novaeseelandiae), was more likely to be aggressive at feeders with higher sugar concentrations but foraged longer at feeders with lower sugar concentrations. Neither feeder presence nor sugar concentration influenced garden bird species richness or abundance. We discuss the effects of sugar-water feeding on bird behaviour at the global and local scale and suggest future study directions.

KEYWORDS:

• Avian behaviour
• nectarivorous species
• supplementary feeding
• sugar feeders
• urban ecology

Acknowledgements

We are grateful for all the household volunteers who participated in this study. We thank Alan Fredy, Alex and Mary Kaliukin, Antoine Filion, Casey Patmore, Cathy Nottingham, Ellen Hume, Meg Spittal, Rosie Gerolemou, Roisin Normanly, and Sandra Anderson, for help with conducting the fieldwork. We are grateful to two anonymous reviewers for their helpful advice. The University of Auckland Animal Ethics Committee (approval No. 002100) approved the research.

Data availability statement

Original datasets from this study are available at: https://figshare.com/articles/dataset/direct_behavioural_bird_observations_existing_sugar_water_feeders_Auckland_Dinedin_2018-2019/15153552; https://figshare.com/articles/dataset/direct_behavioural_bird_observations_experimental_sugar_water_feeders_Auckland2020/15133860; https://figshare.com/articles/dataset/Untitled_Itemgarden_bird_counts_experimental_suagr_water_feeders_Auckland_2019-2020/15133950; https://figshare.com/articles/dataset/experimental_sugar_water_feeders_camera_data_photo_Auckland_2019-2020/15133911; https://figshare.com/articles/dataset/experimental_sugar_water_feeders_camera_data_video_Auckland_2020/15133932.

Disclosure statement

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

Geolocation information

This study was conducted in Auckland (36°50ʹ54”S, 174°45ʹ48”E) and Dunedin (45°52′27″S, 170°30′13″E), New Zealand.

Supplementary material

Supplemental data for this article can be accessed at https://doi.org/10.1080/01584197.2022.2132961

Additional information

Funding

This work was supported by the Royal Forest and Bird Protection Society of New Zealand under James Sharon Watson Conservation Trust fund (2018);by Ornithological Society of New Zealand under Research Fund (2018);by Waipapa Taumata Rau, the University of Auckland under University of Auckland Doctoral Scholarship;and by Manaaki Whenua Landcare Research, Centre for Biodiversity and Biosecurity under Centre for Biodiversity and Biosecurity Project Fund (2018) and Publication Stipend (2021).