Differences in the ages, sexes and physical condition of Starlings Sturnus vulgaris at the centre and periphery of roosts

Abstract

The differences between individuals at the centre and at the periphery of social groupings of birds have been demonstrated, but night‐time roosts have received little attention. Here, the effects of age, sex and physical condition on the structure of Starling roosts were investigated. It was found that the dispersion of different age and sex categories was heterogeneous; proportionately more adult males occurred in the centre compared with the periphery, and proportionately more first‐year females occurred on the periphery compared with the centre. Birds in the centre were heavier than peripheral ones irrespective of differences in body‐size. We propose that the centre of the roost is the preferred location and that the observed dispersion reflects dominance.

ZENK labeling within social behavior brain regions reveals breeding context-dependent patterns of neural activity associated with song in male European starlings (Sturnus vulgaris)

“…Studies in mammals and birds implicate the BST and LS in dominance, aggression, and social signaling used to maintain dominance status [7,9,15,36,38,45,65]. In European starlings, it has been suggested that song produced outside breeding context is used to establish and/or maintain social hierarchies within the large, overwintering flock [64]. Thus, positive linear relationships between ZENK in BSTm(v) and LSc.v and non-breeding context song might reflect a conserved role for the BST and LS in the regulation of social signaling and dominance relationships across vertebrates.…”

“…testosterone (T)) are low [6,56], and male and female starlings are found feeding and roosting in large, mixed-sex flocks [20]. At this time, song appears to play no direct role in mate attraction [57], but rather is thought to be important for flock cohesion and establishing/maintaining social hierarchies within the flock [31,64]. Thus, starling song produced in a non-breeding context appears to be broadly socially motivated.…”

Structural Changes between Seasons in the Songbird Auditory Forebrain

“…Male starlings sing throughout the year, but during the breeding season (spring), when concentration of plasma testosterone (T) is elevated, singing behavior can be highly sexually motivated (Riters et al, 2000). In the nonbreeding season, when plasma concentration of T is basal (Ball and Wingfield, 1987;Riters et al, 2002), song rather plays a role in social interactions such as maintenance of cohesion and of dominance hierarchies within the flock (Summers et al, 1987;Hausberger et al, 1995;Eens, 1997). As such, male European starlings are an ideal model system to explore seasonal neural plasticity of singing behavior.…”

Winter weights and age structure of a population of pied wagtails at a Southern Scotland roost

“…Structured roosts are known in several bird species, for example in the Red-winged Blackbird Agelaius phoenicius (Weatherhead & Hoysack 1984), where older males occupied the centre of roosts while younger males remained on the periphery; in the Rook Corvus frugilegus (Swingland 1977) where more adults than young birds roosted in the tops of trees than at lower levels; and in the Starling Sturnus vulgaris (Summers, Westlake & Feare 1987). With the Starling it has been shown that the dispersion within roosts of different age and sex categories was heterogeneous: proportionately more adult males occurred in the centre compared with the periphery and more first-year females occurred around the periphery than in the centre.…”

“…Birds roosting in the centre were heavier than those from peripheral areas, even allowing for differences in body size as indicated by winglength measurements. Summers et al (1987) proposed that the centre of the roost is the preferred location and that the observed dispersion within it reflects dominance, which is a function of age (adult birds dominate first-years), sex (males dominate females) and physical characteristics (heavier birds dominate lighter ones). In the Starling, dominance is established by intraspecific aggression over roosting places following arrival at the roost.…”