How to Get the Girl: The (Spatule)Tale           

It’s hard to get the girl. In the case of the marvelous spatuletail hummingbird (Loddigesia mirabilis), males need more than just pretty looks — they need stamina, as shown in Episode 5 of David Attenborough’s Life Season 1. Males of this species are unique in one particular feature: their spatules (or rackets) [1]. The male uses these spatules — two long, modified tail feathers ending in blue-violet discs — as “flags” to attract female hummingbirds in dances [1, 2]. The dramatic movement of the spatules can even make sounds like castanets to capture the attention of the female [3]. These flamboyant displays may be attractive, but flying with these spatules takes a lot of energy [3, 4]. Although this feature makes it harder for males to fly, the advantage of attracting females and increasing their chances of reproducing greatly outweighs the energetic costs of flying with spatules [3, 5]. These spatules likely have arisen due to sexual selection [3].

Sexual selection is the preference for certain traits in different sexes, and exaggerated cases of sexual selection may lead to sexual dimorphism, which occurs when males and females of the same species look distinctly different. In the case of the marvelous spatuletail hummingbird, females look relatively plain. They have green feathers on top and white below, while males have turquoise feathers that end in violet-blue, wirelike spatules [2]. These spatules are not unique to this species; they are also found in booted rackettail hummingbirds, racket-tailed coquettes, and most species of motmots [2]. So watch out, men — the next male bird that your lady sees may just sweep her off her feet!

by Tulasi Kadiyala, Esther Lee and Linda Li

Life, Season 1, Episode 5 (Birds), starting at 2:36

References

1. Bleiweiss R. 1987. Development and evolution of avian racket plumes: Fine structure and serial homology of the wire. Journal of Morphology 194: 23-39.
2. Shany N. 2006. The butterfly bird: a legendary hummingbird draws bird-watchers to the Peruvian Andes, but the details of its biology and ecology remain largely unknown. Natural History 115(1): 24-27.
3. Zusi RL & FB Gill. 2009. The marvelous tail of loddigesia mirabilis (trochilidae). The Auk 126(3): 590-603.
4. Clark CJ. 2010. The evolution of tail shape in hummingbirds. The Auk 127(1): 44-56.
5. Balmford A, Thomas ALR, & Jones IL. Aerodynamics and the evolution of long tails in birds. Nature 361: 628-631.