Sex-Specific Movements in Postfledging Juvenile Ovenbirds (Seiurus aurocapilla)

摘要

Understanding sex-specific differences in behavior and survival is essential for informative population modeling and evolutionary biology in animal populations. Uneven sex ratios are common in many migrant passerine species; however, the underlying mechanisms remain unclear. We used molecular sex determination, nest monitoring, and radio telemetry of fledgling Ovenbirds (Seiurus aurocapilla), to determine if sex-specific patterns of production, survival or behavior were present prior to the first migration. We tested whether: 1) sex ratios were skewed towards males at fledging; 2) postfledging survival of males was higher than females; 3) distances moved over time were equal between sexes; and 4) if observed parental care was equal between sexes over time. We determined the sex of 33 hatch-year Ovenbirds in central Missouri in 2015 and followed 19 individuals using radio telemetry. We found no difference in sex ratios within broods, overall numbers of male (n = 18) and female (n = 15) nestlings, or in the survival of male (n = 8) and female (n = 11) fledglings followed with radio telemetry. However, we did find that sex affected the relationship between age and distance moved from the nest, suggesting females moved further from the natal site after independence from adults. These results provide a better understanding of postfledging ecology and support the common assumption that annual production of females is half of total productivity, a fundamental premise in most population growth models.