Variation in food supply, time of breeding, and energy expenditure in birds.
D000818:Animals; D004734:Energy Metabolism; D005247:Feeding Behavior; D005260:Female; D005502:Food; D008297:Male; D009425:Nesting Behavior; D012044:Regression Analysis; D012098:Reproduction; D012621:Seasons; D020308:Songbirds / Q000502:physiology*; D013696:Temperature