Female Attraction to Higher Pitched Male Enticement Calls in Barn Swallows

Abstract

Current sexual selection studies demonstrate that female mate preference almost always favors exaggerated male traits, such as colorful plumage and elongated tails. However, such studies focused mainly on secondary sexual characteristics, i.e., traits that are fully developed at maturation, while ignoring others, which precludes generalization of the findings. We studied the expression of the male enticement call, a nestling‐like courtship trait, in relation to female attraction and to the expression of secondary sexual ornaments in the Japanese barn swallow Hirundo rustica gutturalis. First, we showed that the peak amplitude frequency of male enticement calls was, on average, lower than that of nestling food‐begging calls, indicating that higher pitched calls are more similar to nestling food‐begging calls than are lower pitched calls. Second, we conducted an experimental playback of male enticement calls during the courtship period with the female's mate removed, and found that females were more attracted to heightened‐pitch calls than to control calls. Lastly, the peak amplitude frequency of male enticement calls was negatively related to the ornamentation, as measured by throat coloration. Taken together, these findings suggest the following: (1) females are attracted to a more nestling‐like trait, and (2) similarity to nestling food‐begging calls increases with decreasing secondary sexual ornaments. Nestling‐like male traits that are not secondary sexual characteristics should be considered when studying the general pattern of female attraction to male traits.

Beauty alone is insufficient: female mate choice in the barn swallow

“…1 in Hasegawa et al 2013) and unpaired females are similarly attracted to the playback of nestlings' food-begging calls and male enticement calls. Hasegawa and Arai (2016) further demonstrated that unpaired females were more attracted to heightened-pitch (i.e., more nestling-like) calls than to control enticement calls (though female swallows prefer lower, rather than higher, pitched songs; Garamszegi et al 2005Garamszegi et al , 2006. Because male enticement calls pitched lower than typical nestling food-begging calls, the similarity to nestlings decreases with maturation at least in pitch height.…”

“…In addition, nestling-like traits should be related to male secondary sexual characteristics, although a negative relationship can be predicted in this case, because nestling-similarity decreases with maturation, which contrasts with secondary sexual characteristics that increase with maturation (see above; Table 1). Hasegawa and Arai (2016) found that males with less-colorful throat patches emitted more nestlinglike calls. This can also be interpreted as less-ornamented males can still attract females with more nestling-like vocalizations (i.e., they are alternative female attractants; Candolin 2003), maintaining the variation in these traits or even predicting a negative evolutionary relationship between them.…”

“…Interrelationships between female preference for secondary sexual characteristics and other male traits have, unfortunately, not yet been reported but may also be interdependent. For example, it is unlikely that individual preference for male enticement calls has no influence on preference for male song (even if females, on average, prefer higher-pitched enticement calls and lower-pitched song; Hasegawa and Arai 2016;Garamszegi et al 2005Garamszegi et al , 2006. In addition, it is likely that the benefits and costs of choosing well-ornamented males depend on whether they hold high-quality territories (i.e., whether they can avoid nest predation or parasitism), as explained in the next subsection.…”

“…In the barn swallow, enticement calls (Turner 2006, p. 64) are noticeable vocalizations emitted during pairing courtship ( Fig. 1; also see supplementary sounds in Hasegawa and Arai 2016 for some examples). Given the resemblance to nestling food-begging calls, male enticement calls may Fig.…”

Differential visual ornamentation between brood parasitic and parental cuckoos

“…() experimentally demonstrated that unpaired females are attracted to nestling food‐begging calls as well as to male enticement calls that structurally resemble the nestling food‐begging calls in a similar manner. They subsequently found that heighten pitched enticement calls, which resemble nestling food‐begging calls to a greater extent, attract females more, supporting that more nestling‐like trait is more attractive (Hasegawa & Arai, ; note that female swallows prefer lower‐pitched songs; Garamszegi et al ., , ). This example supports the sensory trap exploiting female parental care in a species with parental care, but its relationship to parental care on an evolutionary timescale remains unclear.…”