Early breeding teal Anas crecca use the best lakes and have the highest reproductive success.

Teal (Anas crecca) broods were studied in 1988-2003 in a boreal watershed comprising 51 permanent wetlands. Brood size of near-fledged ducklings was negatively related to the hatching date, i.e. early pairs had higher reproductive success than late pairs. However, brood size of newly hatched ducklings was not related to the hatching date, implying that the advantage of early breeding is due to processes operating during the brood stage rather than during nesting. Half of the lakes never produced a brood, and among the 26 lakes that actually did, two preferred’ lakes generated 44% of the broods and 55% of the near-fledged ducklings. Early broods were over-represented on such preferred’ lakes, and late broods over-represented on less preferred’ lakes. Our study suggests that lake selection and early nesting may have important fitness consequences in teal.

Elmberg, J., Nummi, P., Poysa, H., Gunnarsson, G. & Sjoberg, K. 2005, Ann. Zool. Fennici 42: 37-43