Effect of the Social Environment on Spring Migration Timing of a Songbird

Abstract

The influence of the social environment on the timing of the annual cycle is poorly understood. Seasonally migratory birds are under pressure to accurately time their spring migration, and throughout the annual cycle, they may experience variability of the local sex-ratio. A population-level male-biased sex ratio is predicted to advance spring migration timing in males and is attributed to the increased intra-specific competition for access to females and/or breeding territories. The present study had two goals. First, to develop a method that utilizes digitally coded radio-transmitters to quantify the activity of flocked individuals in captivity. Second, to use this method to test the hypothesis that the social environment influences the spring migration traits of male yellow-rumped warblers (Setophaga coronata coronata). To accomplish this, birds were captured in the fall in Long Point, Ontario, and transferred to the Advanced Facility for Avian Research, London, Ontario. In the winter, they were assigned to a slightly male- or female-biased treatment and housed in flocks in large free-flight rooms. Throughout the experimental period, we took body mass measurements and standardized photos to monitor body condition and molt progression. To measure locomotor activity, the birds were outfitted with digitally coded radio-transmitters in April and photo-triggered to enter a migratory phenotype. The tagged birds were released at their capture site in May and the Motus Wildlife Tracking System was used to determine stopover departure timing and migratory movements. Sex ratio did not influence body mass or molt progression. However, males from the male-biased treatment had significantly less locomotor movement than those from the female-biased treatment. Additionally, a lower proportion of males from the male-biased treatment initiated migratory restlessness, an indicator of the urge to migrate. Overall, these findings suggest that the social environment can influence behavior of songbirds, but do not support the hypothesis that a male-biased sex ratio accelerates migration.

Genetic Analysis Reveals Dispersal Patterns of Japanese Serow in Two Different Habitats of a Mountainous Region

“…Furthermore, as previously discussed, natal habitat-biased dispersal may lead to philopatric dispersal of males in grassland. Recent genetic analyses suggested variability in sex-biased dispersal patterns in some ungulates (Pérez-Espona et al, 2010;Deakin et al, 2021). More detailed genetic studies of ungulates in various environments will elucidate the effects of the social system and environment on dispersal patterns in detail.…”

More than mortality: Consequences of human activity on migrating birds extend beyond direct mortality

“…Migrants in flight can use social information from other birds, including acoustic cues, when deciding where to land (Chernetsov 2006, Mukhin et al 2008, Németh and Moore 2014). Migrants also use social learning to assess the location of food resources, competitors, and predators at unfamiliar stopover sites (Németh and Moore 2007, Deakin et al 2021, Aikens et al 2022). Consequently, noise pollution that masks acoustic cues from avian communities, prey, or predators may reduce birds' ability to quickly and safely refuel, affecting their condition and migration timing, and ultimately their fitness.…”