Altered body condition, increased incubation costs, and egg loss are important proximate factors modulating bird parental behavior, since they inform the adult about its remaining chances of survival or about the expected current reproductive success. Hormonal changes should reflect internal or external stimuli, since corticosterone levels (inducing nest abandonment) are known to increase while...

Egg storage longer than 7 d is associated with a delay in hatch time and a decline in hatchability and chick quality. Prestorage incubation is suggested as a method to reduce the negative effects of prolonged storage times by altering the developmental stage of the embryo, but earlier research has shown that prestorage incubation can both be detrimental and beneficial for hatchability. The reas...

BACKGROUND Long-lived seabirds face a conflict between current and lifelong reproductive success. During incubation shifts, egg neglect is sometimes necessary to avoid starvation, but may compromise the current reproductive attempt. However, factors underlying this decision process are poorly understood. We focus on the ancient murrelet, Synthliboramphus antiquus, an alcid with exceptionally lo...

Female birds may optimize reproduction by modifying clutch size and the timing for the onset of incubation. We measured fecal estradiol-17beta (E) and progesterone (P) in laying canaries to better understand how onset of incubation might regulate clutch size. Both E and P rose sharply to maxima 1 day before the first egg was laid. Thereafter, E steadily declined, but P remained high through 2 d...

The incubation of eggs is strongly influenced by temperature as observed in all species studied to date. For example, incubation duration, sexual phenotype, growth, and performances in many vertebrate hatchlings are affected by incubation temperature. Yet it is very difficult to predict temperature effect based on the temperature within a field nest, as temperature varies throughout incubation....

hhderhalden and Kempe (1) analyzed the hen’s egg for glutamic acid, glycine, and tyrosine on the lst, lOth, and 21st day of incubation. Their results indicated that the amounts of these acids remained constant throughout the incubation period. Investigations carried out by Calvery (a-4), Plimmer and Lowndes (5), Schenck (6), and Sendju (7, 8) indicate that variations occur in the amounts of arg...