Testosterone levels in relation to size and UV reflectance of achromatic plumage traits of female pied flycatchers

Abstract

In a substantial number of species, females show some development of secondary sexual characters. These traits can function as signals of individual phenotypic or genetic qualities and status to conspecifics. Individuals may benefit potentially from expressing signals or badges of status if they are reliable and honest signals of individual quality. In many species, badge sizes have been shown to correlate with dominance rank, which may be mediated by testosterone (T) levels. Here, we explored geographic variation in the size and properties of the white wing patch of female pied flycatchers Ficedula hypoleuca and its relation to circulating T levels in three populations (two southern populations in central Spain and a northern population in Finland). Furthermore, we aimed at detecting if the size of the white wing patch and its ultraviolet (UV) reflectance indicate individual quality. We found that females in Spain had larger, brighter and more UV reflecting wing patches than those in Finland. Females with higher UV reflectance and larger primary white patches bred earlier. Younger females and females with larger primary white wing patches showed higher T levels. In contrast, higher values of UV reflectance in feathers from these patches were associated with low T levels. Despite genetic differentiation and differences in trait expression between populations, female pied flycatchers from different populations may converge and use the size of white wing patches to signal their T levels and thereby their social dominance.

Phenotypic plasticity in breeding plumage signals in both sexes of a migratory bird: responses to breeding conditions

“…In this study we focus on the area of these plumage patches as in other studies of the species (Galván and Moreno 2009, Lehtonen et al 2009a, Moreno et al 2011, Plaza et al 2018. Moreover, we have previously shown that area and UV reflectance of wing patches are positively correlated, at least in females (Cantarero et al 2017). More than half of the females (56% in the study years) exhibit no measurable forehead patch in our populations.…”

“…Forehead patches are moulted together with body plumage in Africa, while wing patches are constituted by white patches on tertials, also moulted in Africa, and white bands on flight feathers, moulted in the breeding range during or soon after breeding (Lundberg and Alatalo ). The parts of wing patches moulted in the breeding respectively to wintering areas constitute roughly half of the total wing patch each (Cantarero et al ). The expression of achromatic plumage in males varies across the breeding distribution, with males of Spanish populations exhibiting the largest white forehead and wing patches (Lehtonen et al , Laaksonen et al ).…”

“…UV reflectance of white patches has been analyzed in other studies of the species (Lehtonen et al , Sirkiä and Laaksonen ). In this study we focus on the area of these plumage patches as in other studies of the species (Galván and Moreno , Lehtonen et al , Lobato et al , Moreno et al , , , Cantarero et al , , Laaksonen et al , Sirkiä et al , Plaza et al ). Moreover, we have previously shown that area and UV reflectance of wing patches are positively correlated, at least in females (Cantarero et al ).…”

“…It is a longdistance migrant between its Western Palearctic breeding distribution and its African wintering range (Lundberg and Alatalo 1992). Both sexes present white patches on the wings and on the forehead, although female forehead patches are almost nonexistent in northern populations (Morales et al 2007, Cantarero et al 2017. There is a large literature showing that these patches constitute sexual and social signals of differing importance according to the population being studied (Dale et al 1999, Morales et al 2007, Galván and Moreno 2009, Lehtonen et al 2009a, Sirkiä and Laaksonen 2009, Moreno et al 2011, Järvistö et al 2013, Plaza et al 2018, Teerikorpi et al 2018.…”

Nestling sex ratio is associated with both male and female attractiveness in rock sparrows

“…The evolution of female ornamental traits has been considered to be a genetically correlated response to selection for male ornamentation (Lande 1980, Amundsen 2000. However, numerous studies show that females acquire fitness advantages by deterring conspecific rivals and/or attracting mates (Amundsen 2000, Morales et al 2007, Hegyi et al 2008, Griggio et al 2009, Roulin et al 2010, Cantarero et al 2017a, Plaza et al 2018, indicating that ornamental trait evolution in females may have its own functionality and can be at least partly explained by sexual selection (Tobias et al 2012). Indeed, there is evidence that female ornamental traits could act as signals of individual quality (Hanssen et al 2006, Morales et al 2007), fecundity (Potti et al 2013) or reproductive investment (Wright et al 2008).…”