Patterns of maternal yolk hormones in eastern screech owl eggs (Megascops asio)

► Yolk hormone patterns within-clutch and within-yolk were studied in the screech owl. ► Influence on nestling food allocation and developmental origin are both considered. ► Yolk androgens were lower in first-laid eggs, which may reduce dominance of first chick. ► Both androgens were lower in outer yolk layer, consistent with follicular origin. ► Corticosterone was evenly distributed within yolk, consistent with adrenal origin.