Onset of Incubation and Patterns of Hatching in the American Coot

Abstract

Abstract. Examining incubation behavior during laying and that behavior's consequences on patterns of hatching can help discriminate among hypotheses competing to explain the evolution of asynchronous hatching. Consequently, I documented nest attentiveness and patterns of hatching of American Coots (Fulica americana) nesting in southwestern Manitoba from 1986 to 1991. Coots gradually increased their nest attentiveness from laying of the first to the sixth egg, and attentiveness to late-season clutches peaked earlier during laying, but it was unaffected by clutch size, first vs. replacement nest, or supplemental food. Nest attentiveness during laying was effective at initiating embryo development, as evidenced by a strong positive correlation between the order of laying of eggs and order of hatching of chicks. These results are most consistent with hypotheses that nest attentiveness during laying evolved to protect eggs or maintain viability of embryos. Clutch-initiation date had the most pronounced effect...