Fledgling Sex Ratio Is Determined by Egg Loss, Hatching Order, Nestling Mortality, and Inter-Annual Food Fluctuations for Boreal Owls, <i>Aegolius funereus</i>.

ABSTRACT: Extensive research has been conducted to explore adaptive variation in offspring sex ratios, focusing on birds as a model group. However, studies to date have not been comprehensive in scope, limiting our understanding of whether there is substantial within- or among-year variation in offspring sex ratios, which environmental conditions and mechanisms are associated with this variation, and when during a nesting attempt the fledgling sex ratio is largely determined. To address these gaps, we analyzed our 18-year dataset from 542 sexually size-dimorphic Boreal Owl (Aegolius funereus) offspring in 140 nests. At hatching, within-nest variation in hatching order emerged as the primary predictor of sex ratio, with later-hatched offspring more likely to be female in larger broods when one

SUBMITTER: Zarybnicka M 

PROVIDER: S-EPMC11906283 | biostudies-literature | 2025 Mar

REPOSITORIES: biostudies-literature