Female-female competition is influenced by forehead patch expression in pied flycatcher females

Abstract

24There is increasing evidence that sexual selection operates in females and not only in males. 25However, the function of female signals in intrasexual competition has been little studied in 26 species with conventional sex roles. In the Iberian populations of the pied flycatcher (Ficedula 27 hypoleuca), some females express a white forehead patch, a trait that in other European 28 populations only males exhibit and has become a classical example in studies of sexual 29 selection. Here, we investigated whether the expression of this trait plays a role in female-30 female competition during early breeding stages. To test this hypothesis, we simulated 31 territorial intrusions by challenging resident females with stuffed female decoys expressing or 32 not a forehead patch. We found that resident females directed more attacks per trial and 33 maintained closer distances to non-patched decoys than to patched ones. Also, patched 34 females were more likely to attack the decoy than non-patched females. Interestingly, females 35 were more aggressive against the decoys when their mate was absent. This may indicate that 36 females relax territory vigilance in the presence of their mate or that males interfere in the 37 interaction between competing females. The behavior of resident males was also observed, 38 although it was not affected by decoy's patch expression. Our findings suggest that the 39 forehead patch plays a role in female intrasexual competition. If the forehead patch signals 40 fighting ability, as it does in males, we may interpret that non-patched females probably 41 avoided repeating costly agonistic encounters with the most dominant rivals. 42 43

Female aggressiveness towards female decoys decreases with mate T level in the pied flycatcher

“…Thus, males may affect female territorial behaviour through their capacity to exclude intruding males (Kellam et al 2006;Moreno et al 2013). Accordingly, it has been shown that male absence may increase female aggressiveness, suggesting that females take on extra costs of territoriality when their mates are not present (Morales et al 2014). More dominant males are expected to exclude male intruders more efficiently, and this could positively affect female physiological state (Moreno et al 2013).…”

Female Song Rate and Structure Predict Reproductive Success in a Socially Monogamous Bird

“…Social selection (defined in West-Eberhard, 1979) focuses on the role of social interactions as drivers of selection, regardless of whether the interaction is sexual or non-sexual Tobias et al, 2012). Although still not widely embraced and somewhat controversial, social selection predicts that the strength of social interactions may determine how aggressive traits such as vocalizations, coloration, weapons, and ornaments correlate with measures of reproductive success (McComb et al, 1994;Friedman et al, 2009;Cornwallis and Uller, 2010;Santana et al, 2012;Tobias et al, 2012;Morales et al, 2014).…”

Determinants of making success in female Tree Swallows (Tachycineta Bicolor)

“…Although studies have demonstrated that such traits function as signals of quality that are preferred by males (Griggio et al, 2005;Torres and Velando, 2005) and are important in agonistic interactions (Griggio et al, 2010;Midamegbe et al, 2011;Morales et al, 2014), Ornamental traits of females that are preferred by males may influence their investment in reproduction (Edward, 2015). For instance, variation in the attractiveness of ornamentation displayed by females may influence how much parental care males invest in the current reproductive attempt (Burley, 1986;Sheldon, 2000).…”

“…In line with this, Moreno et al (2013) reported that non-ornamented female pied flycatchers manipulated to display a forehead patch had higher oxidative damage compared to control females and hypothesized that competition for limited nest sites may enforce the honesty of female ornamentation. Territorial defence by resident female birds toward decoy intruders is strongly influenced by the ornamentation of both the resident and intruding female (Midamegbe et al, 2013;Morales et al, 2014), which may suggest that nest site intrusions by conspecific females provides a mechanism to enforce the honesty of quality signals, but to my knowledge this has never been experimentally tested in free-living female birds.…”

“…Such traits may act directly as weaponry (Watson and Simmons, 2010b) and/or signal the competitive ability or status of females (Pryke, 2007;Midamegbe et al, 2013;Morales et al, 2014).…”