Individual quality and food availability determine yolk and egg mass and egg composition in tree swallows Tachycineta bicolor

• DOI: 10.1111/j.2006.0908-8857.03624.x
• Publication Date: 2006-03-29T15:19:59Z
• Authors: Daniel R. Ardia; Matthew F. Wasson; David W. Winkler
• Keywords: Yolk; Bird egg

Variation in egg size and composition can have important consequences for the quality of offspring. We investigated factors influencing yolk mass tree swallows breeding Ithaca, NY. Using a nondestructive technique to estimate via standardized digital‐candler photographs, we compared Tachycineta bicolor response variation food availability individual quality. Insect one three days prior laying, but not four six days, predicted mass, while insect two laying total mass. This suggests that, eggs are formed over longer periods, closer time has greatest influence on size. These results were supported by collected eggs, as rings revealed that swallow 5–6 days. There was an female well, with early birds, independent availability, larger eggs. Eggs laid later sequence had yolks greater Overall, appears be due combination environmental conditions, reflected resources, quality, allocation tradeoffs during period.