Biparental incubation behaviour under temperature extremes in sandbank nesting black skimmers

• Published in: Ecology and evolution Vol. 14; no. 2; pp. e11021 - n/a
• Main Authors: Austad, Martin, Sand Sæbø, Jørgen, Steen, Ronny, Goodenough, Katharine S., Davenport, Lisa, Haugaasen, Torbjørn
• Format: Journal Article
• Language: English
• Published: England John Wiley & Sons, Inc 01.02.2024; John Wiley and Sons Inc; Wiley
• Subjects: Amazonia; Ambient temperature; Beaches; Behavioural Ecology; Birds; Dimorphism; Environmental risk; Females; Floods; Incubation; Incubation behavior; Nesting; Nests; Photography; Predation; Rivers; Rynchops niger; Sexual dimorphism; thermal ecology; time‐lapse; Water level fluctuations; Water levels; Manu River; United States > US; Amazonia; thermal ecology; Rynchops niger; time‐lapse
• ISSN: 2045-7758; 2045-7758
• DOI: 10.1002/ece3.11021

Birds nesting on riverine beaches are exposed to large temperature fluctuations, while changing water levels pose flooding risks. We used miniature temperature loggers (iButtons®) placed in nests and on the beach surface combined with time‐lapse photography to study incubation behaviour in the black skimmer (Rynchops niger) on the Manu River, Peru. Since the species exhibits sexual size dimorphism, we could identify partner switches in images and the contribution to incubation effort by each pair member. Results of the study documented that nest temperature was less affected by ambient temperature and fluctuated less than the surroundings. Despite shorter incubation bouts at midday, black skimmers maintained a close to constant presence at the nest by more frequent nest exchanges. In fact, while female black skimmers generally incubated more and for longer than males, pairs shared incubation most consistently during the hottest part of the day. Incubation probability decreased around dusk, a peak foraging time for the species and a time when beach temperature overlapped with nest temperature. A biparental incubation strategy across the diel cycle appears to allow black skimmers breeding at the Manu River to incubate in challenging thermal conditions, but further studies are needed to determine proximity to thermal limits. We investigated biparental incubation behaviour and nest temperature using autonomous recording devices and test whether male and female time budgets change across the diel cycle in a sexually dimorphic species. Black skimmers made use of several behavioural mechanisms, such as shorter incubation bouts, higher pair synchronisation and thermoregulatory postures to maintain high nest attendance even in the hottest part of the day. Our findings can inform habitat management and conservation which are increasingly needed for sandbank nesting species.