Food provisioning and brooding behaviors of orange-crowned warblers

Measures of parental provisioning and brooding effort by the sexes of orange-crowned warblers breeding in Fairbanks, Alaska (Oreothlypis celata celata; AK) and on Santa Catalina Island, California (O. c. sordida; CA) in the early (day 3 after hatching) and late (day 6 in Alaska; day 7 in California) nestling stages: (1) per-trip food loads scored as one if the volume of food load was equal to the beak size (see Methods), (2) hourly feeding trips, (3) hourly food delivery rate (the number of feeding trips × food load / hr), (4) proportional female brooding time (brooding min / videotaped min), and (5) ambient temperature (degrees Celsius).