Tail flaring during agonism in hummingbirds
4 affiliations
- 1Field Research Station at Fort Missoula, Division of Biological and Biomedical Sciences, University of Montana, Missoula, MT 59812, USA
- 2Department of Mechanical Engineering, Pennsylvania State University, University Park, PA 16802, USA
- 3Department of Biological and Molecular Sciences, George Fox University, Newberg, OR 97132, USA
- 4Department of Mechanical Engineering, Vanderbilt University, Nashville, TN 37235, USA
Abstract
Bird tails in flight generate lift, reduce pressure drag and stabilize pitch. Hummingbirds can sustain hovering in still air and generate lift in both the upstroke and downstroke owing to their proportionally enormous primary flight muscles and derived wing skeleton. Given their mass-specific wing power, it is possible that tails are less essential to the aerodynamics of hummingbird flight than they are in other birds, freeing them for non-locomotor functions. Hummingbird tails are well known for their morphological elaboration as sexually selected ornaments, including sound generation. From informal observations of agonism, we hypothesized that tail flaring may also be a visual signal used by males during fighting. To begin testing this, we measured the frequency and magnitude of tail flaring during fighting. We measured kinematics of tail flaring during male–male fighting of calliope hummingbirds (Selasphorus calliope, n=10) indoors. Consistent with our hypothesis, captive males exhibited greater angles of tail flare when engaged in a fight (34.6±45.5 deg, mean±s.d.) than when performing solitary landing (−14.2±9.12 deg) and take-off (−14.1±7.0 deg) maneuvers. When birds won a fight, the angles of their tail spread were greater than when they lost. Moreover, recordings of seven species of hummingbird in the field revealed 95% of interspecific and intraspecific contests included tail flaring. We evaluate these results in the context of signaling during animal contests and propose future tests of whether tail flaring is an honest signal of individual quality and resource holding potential.
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BibTeX
@article{elting2026tail,
title = {{Tail flaring during agonism in hummingbirds}},
author = {Rosalee Elting and Md Zafar Anwar and Donald R. Powers and Bo Cheng and Haoxiang Luo and Bret W. Tobalske},
journal = {The Journal of Experimental Biology},
year = {2026},
month = oct,
doi = {10.1242/jeb.253064},
url = {https://doi.org/10.1242/jeb.253064},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Tail flaring during agonism in hummingbirds
AU - Rosalee Elting
AU - Md Zafar Anwar
AU - Donald R. Powers
AU - Bo Cheng
AU - Haoxiang Luo
AU - Bret W. Tobalske
PY - 2026
DA - 2026/10/07
JO - The Journal of Experimental Biology
DO - 10.1242/jeb.253064
UR - https://doi.org/10.1242/jeb.253064
AB - Bird tails in flight generate lift, reduce pressure drag and stabilize pitch. Hummingbirds can sustain hovering in still air and generate lift in both the upstroke and downstroke owing to their proportionally enormous primary flight muscles and derived wing skeleton. Given their mass-specific wing power, it is possible that tails are less essential to the aerodynamics of hummingbird flight than they are in other birds, freeing them for non-locomotor functions. Hummingbird tails are well known for their morphological elaboration as sexually selected ornaments, including sound generation. From informal observations of agonism, we hypothesized that tail flaring may also be a visual signal used by males during fighting. To begin testing this, we measured the frequency and magnitude of tail flaring during fighting. We measured kinematics of tail flaring during male–male fighting of calliope hummingbirds (Selasphorus calliope, n=10) indoors. Consistent with our hypothesis, captive males exhibited greater angles of tail flare when engaged in a fight (34.6±45.5 deg, mean±s.d.) than when performing solitary landing (−14.2±9.12 deg) and take-off (−14.1±7.0 deg) maneuvers. When birds won a fight, the angles of their tail spread were greater than when they lost. Moreover, recordings of seven species of hummingbird in the field revealed 95% of interspecific and intraspecific contests included tail flaring. We evaluate these results in the context of signaling during animal contests and propose future tests of whether tail flaring is an honest signal of individual quality and resource holding potential.
SN - 0022-0949
SN - 1477-9145
ER -