Female mate choice based on territory quality in barn swallows

Abstract

Female mate choice based on territory quality is difficult to study because territories often contain many resources, which are difficult to quantify. Here, using the barn swallow (Hirundo rustica gutturalis) breeding at an outdoor breeding site in Japan, where each male defends only a small territory containing old nests, we studied whether females choose social mates based on territory quality. Since the territories of this species contain few other resources, territory quality can easily be assessed by quantifying old nests in the territory. We made the following four observations: (1) male swallows displayed old nests in their territories to females; (2) the old nests used for the first clutch were less broken than the other old nests within the same territory; (3) territory quality, defined by the number of old nests weighted by the intactness of each old nest, predicted the productivity of the territory; and (4) males with better territories paired with females earlier, and hence bred earlier, than those with inferior territories. The relationships remained significant even after controlling for male morphological traits. Based on these results, we can infer that female swallows choose their mates based, in part, on territory quality.

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

“…3). As expected, males with high-quality territories paired earlier, indicating female mate choice based on territory quality (Hasegawa et al 2012a; though there may still be some population differences in the relationship between territory quality and reproductive parameters; see above). Although territory quality is often related to male morphological traits (e.g., throat coloration in this species; Hasegawa et al 2014;Wilkins et al 2015), multivariable analysis indicates that territory quality is an important mate choice criteria than male morphology (in fact, effect size, Zr = 0.60, 95% CI = 0.14-1.06 for laying date and 0.62, 95% CI = 0.11-1.12 for pairing date, computed from R 2 value, is quite high for female preference for territory quality, though sample sizes were small (n = 21, 18, respectively); note that mean overall effect size for plumage ornaments was 0.21; Romano et al 2017a).…”

“…Although territory quality is often related to male morphological traits (e.g., throat coloration in this species; Hasegawa et al 2014;Wilkins et al 2015), multivariable analysis indicates that territory quality is an important mate choice criteria than male morphology (in fact, effect size, Zr = 0.60, 95% CI = 0.14-1.06 for laying date and 0.62, 95% CI = 0.11-1.12 for pairing date, computed from R 2 value, is quite high for female preference for territory quality, though sample sizes were small (n = 21, 18, respectively); note that mean overall effect size for plumage ornaments was 0.21; Romano et al 2017a). As swallows choose high-quality (i.e., intact) nests within their territories (Hasegawa et al 2012a) or choose colonies/breeding sites with many high-quality nests (Safran 2004(Safran , 2007; also see Ringhofer and Hasegawa 2014), it is not surprising that females choose territories with high-quality nests, though experimental validation remains to be carried out. Because territory is not the sole resource provided by males in this biparental care species, it is natural to suppose that other types of resources may also be the targets of female preference.…”

“…2 for nest predation attempt by the carrion crow). In Japan, approximately 50% experience nest failure (Fujita 1993;Hasegawa et al 2012aHasegawa et al , 2017; also see Turner 2006 for the potential importance of crows as nest predators in this region: also see Liang et al 2013;Su et al 2017 for the potential importance of interspecific brood parasitism), though actual predation rates depend on population (e.g., see Møller 2010 for subtle differences between colony and outdoor populations in European subspecies). In Japan, territory quality, measured by the quality and quantity of old nests, predicts seasonal reproductive success (Hasegawa et al 2012a), and males did settle in better territories than their previous terri- tories when they changed territories across years in outdoor breeding sites (Fig.…”

Geographic variation in sexual selection and implications for speciation in the Barn Swallow

“…Even among European populations there is variation the strength of selection on tail length, although it remains consistently positive among populations (Møller et al 2006). Likewise, the information conveyed by these traits varies geographically, with some evidence suggesting that long tail streamers in Europe advertise indirect benefits (Møller 1994a;Møller et al 1998a); but see (Bro-Jørgensen et al 2007) for alternative explanations), whereas coloration has been suggested to advertise direct and indirect benefits in Japan (Kojima et al 2009;Hasegawa et al 2012), and could relate to both direct and indirect benefits in North America (Safran and McGraw 2004;Safran et al 2005). If the relative importance of different types of benefits varies among populations, this may result in mate choice, and consequent directional selection, on different traits, leading to phenotypic divergence and reproductive isolation based on sexually selected signals.…”

Infanticide on a Grown Nestling in a Sparse Population of Japanese Barn Swallows (Hirundo rustica gutturalis)

“…Rather, among the three other adaptive reasons for infanticide (i.e., resource competition, parental manipulation, and exploitation of infants [cannibalism]; Hrdy 1974), resource competition is the most plausible explanation for the current case because the male tried to attract the female mate to the focal nest by emitting enticement calls (i.e., the focal nest is regarded as a candidate breeding nest; Turner 2006, Hasegawa et al 2013. In the sparse populations of Barn Swallows seen in Japan, in contrast with the colonial populations seen in Europe, selection pressure favoring the occupation of well-constructed nests is high to avoid high nest predation by crows (Hasegawa et al 2012; see also Fujita 1993, Suzuki 1998, reviewed in Hasegawa 2011. In fact, in contrast to European colonies, in which nests with dead nestlings generally remain for several years (Møller 2004), parents in Japanese populations often seek breeding nests and use old nests containing dead nestlings; in such cases, the dead bodies are discarded before the onset of breeding (MH, pers.…”