Effect of incubation body mass on reproductive success and survival of two European diving ducks: A test of the nutrient limitation hypothesis

The nutrient limitation hypothesis postulates that variation in nutrient reserves during egg laying and incubation are important predictors of future reproductive success of female waterfowl. We tested one component of this hypothesis in two European diving ducks, Common Pochard (Aythya ferina) and tufted Duck (Aythya fuligula), relating body masses of incubating females to subsequent nest success, and to duckling and adult survival. We based our analyses on 3,224 Common Pochards and 1,812 Tufted Ducks captured and weighed during the last two weeks before ducklings hatched at Engure Marsh, Latvia, in 1978-1993. Adult (ASY) females from successful nests weighed significantly more than those from abandoned nests, but differences in body masses between two categories of nest fates were negligible for yearlings (SY). For both species, survival (measured as apparent return rate) of females (SY + ASY) was unrelated to their body masses. Duckling recruitment was independent of adult female body mass for both species, but yearling Common Pochards that provided recruits weighed more than those that produced none. Results of our study support the nutrient limitation hypothesis and we conclude that nutrient reserve levels may be important determinants of nest success in female ducks in general, especially for species that rely heavily on endogenous reserves during incubation.