What common reproductive division of labor occurs during the incubation period for *T. verticalis*?

The female exclusively handles incubation, while both parents share chick feeding

The mating system established for the Western Kingbird is monogamy, involving a structured division of parental responsibilities vital for raising altricial chicks. While both parents actively contribute to nest building and subsequently share the duty of provisioning food to the young, the energetic demands of brooding are handled solely by one sex during the primary nesting phase. Specifically, the female bird exclusively handles the incubation duties, a process which typically lasts between 12 to 19 days. This strategy—female incubation coupled with biparental provisioning—represents a common reproductive evolution strategy across many avian species, efficiently balancing the high energetic cost of brooding the eggs with the continuous need for constant food delivery required by rapidly developing young.