Abstract
The mouth coloration of nestling birds is hypothesized to be uniquely adaptive during the nestling stage, perhaps signalling condition. To identify nestling-specific colours, we compared adult and nestling gapes in Cave Swallows (Petrochelidon fulva). Nestling gapes reflected more ultraviolet (UV) light and tended to be yellower (because they contained carotenoids). Across broods, heavier nestlings had yellower, less bright, and less UV-rich flanges, and less bright gapes. Nestlings with carotenoid-rich plasma had brighter flanges and yellower gapes. Color did not, however, signal within-brood status. Studies of nestling mouth coloration may benefit from considering complementary and/or competing roles of the trait across ontogeny.
Zusammenfassung
Bei Höhlenschwalben ( Petrochelidon fulva ) unterscheidet sich die Rachenfärbung der Nestlinge von derjenigen der Altvögel, beruht auf Carotinoiden und korreliert mit der Körpermasse
Hypothesen zufolge ist die Innenschnabelfärbung von Vogelnestlingen ein einzigartiges adaptives Merkmal während der Nestlingsphase, welches möglicherweise ein Signal für die Körperkondition darstellt. Um nestlingsspezifische Farben zu bestimmen, verglichen wir die Rachenräume von Altvögeln und Nestlingen bei Höhlenschwalben (Petrochelidon fulva). Der Innenschnabel der Nestlinge reflektierte mehr UV-Licht und war gelber, da er Carotinoide enthielt. Innerhalb der Bruten hatten schwerere Nestlinge tendenziell gelbere, weniger leuchtende und schwächer UV-intensive Schnabelwülste sowie einen weniger leuchtenden Rachenraum. Nestlinge mit carotinoidreichem Blutplasma hatten stärker leuchtende Schnabelwülste und einen gelberen Rachenraum. Die Färbung stellte allerdings kein Signal für den Status innerhalb der Brut dar. Für Untersuchungen der Innenschnabelfärbung von Nestlingen kann es von Vorteil sein, ergänzende oder konkurrierende Rollen dieses Merkmals auf ontologischer Ebene zu berücksichtigen.
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Acknowledgements
We thank J. Place and J. Stoops for assistance with fieldwork and D. W. Mock and two anonymous reviewers for comments on earlier drafts. Funding was provided by the George M. Sutton Scholarship in Ornithology (M. B. D., S. A. S.) and the Purple Martin Conservation Association (M. B. D.). M. B. D. was supported by an Alumni Fellowship in Zoology and S. A. S. by a Blanche Adams Summer Scholarship, both from the University of Oklahoma. The Welder Wildlife Refuge provided housing during fieldwork. All procedures performed in this study were in accordance with the ethical standards of, and approved by, the University of Oklahoma Institutional Animal Care and Use Committee (R06-012, R07-011). This work complied with laws of the USA, and all necessary permits were provided by the US Fish and Wildlife Service and Texas Parks and Wildlife. The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.
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Communicated by L. Fusani.
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Dugas, M.B., McGraw, K.J. & Strickler, S.A. Mouth coloration in nestling Cave Swallows (Petrochelidon fulva) differs from that of adults, is carotenoid based and correlated with body mass. J Ornithol 159, 581–586 (2018). https://doi.org/10.1007/s10336-018-1531-6
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DOI: https://doi.org/10.1007/s10336-018-1531-6