Steller Sex: Infidelity and Sexual Selection in a Social Corvid (Cyanocitta stelleri)

Abstract

Genetic analysis of avian mating systems has revealed that more than 70% of monogamous species show incidence of offspring parentage that does not match the social partner. Extra-pair parentage (EPP) has been linked to a variety of factors, including size and symmetry of ornamental traits, coloration, resource availability, and local conspecific density. We examined how ornamental plumage traits of individual Steller's jays (Cyanocitta stelleri) and territory characteristics influence genetic fidelity of socially monogamous pairs. We used seven highly polymorphic microsatellite markers to assign paternity to 79 offspring, and identified 12 (15.2%) as extra-pair young (EPY). Steller's jays with extra-pair young had significantly lower values of feather brightness and hue, indicating more ultraviolet-blue shifted coloration, and nested in closer proximity to the forest edge than Steller's jays with no detected EPY. Body size, crest height, asymmetry of ornamental crest stripes, as well as vegetative composition of territories and their proximity to supplemental feeders appeared to have little relationship to EPP. These results indicate that extra-pair parentage plays a role in the evolution of secondary sexual characteristics in both sexes, and suggest local density and availability of resources may influence Steller's jay mating dynamics.

Comparing the face inversion effect in crows and humans

“…For example, Steller’s jays’ plumage UV reflection signals mate quality. Note, however, that extra-pair copulations play a relatively important role for Steller’s jays, compared to other corvid species (Overeem et al 2014 ). It is thus unclear whether the importance of UV perception in Steller’s jays’ sexual behaviour is indicative of visual features that might be relevant for monogamous and largely unassisted breeding carrion crows.…”

Deep ecomorphological and genetic divergence in Steller's Jays (Cyanocitta stelleri, Aves: Corvidae)

“…In Steller's Jays, it is possible that brighter and more conspicuous facial features used for visual signaling in open habitats (Rocky Mountain morphotype) may be counterbalanced by selection for darker features (e.g., blue frontal streaks, no superciliary line) that are more cryptic in lower light, closed coastal forest habitats (Coastal morphotype). Plumage traits of individual Coastal Steller's Jays have been found to influence the rate of extra‐pair parentage and the proximity of territories to forest edge (Overeem et al, 2014). While studies have shown that selection in different habitats can be an important driver of phenotypic divergence, the outcome may be clade, environment, or sex‐specific (Cicero et al, 2020; Cornuault et al, 2015; Mason & Bowie, 2020; Medina et al, 2017).…”

Propensity of Predator Mimicry in Steller’s Jays

“…Steller's Jays are relatively tolerant of human proximity; they lend themselves well to the examination of subtle behaviors, thus making jays a particularly well-suited species for behavioral studies. Prior research on this population has described a variety of individual variations in behavioral patterns, including optimal foraging [24], caching effort [25], novel problem solving [27], behavioral syndromes [30], assortative mating [32], and mate fidelity [36]. This research was conducted under the Cal Poly Humboldt Institutional Animal Care and Use Protocol No.…”