Egg temperature and initial brood patch area determine hatching asynchrony in Magellanic Penguin Spheniscus magellanicus

BARRIONUEVO MELINA Y FRERE ESTEBAN

JOURNAL OF AVIAN BIOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2016 vol. 47 p. 16 - 25

0908-8857

In birds, the adaptive significance of hatching asynchrony has been under debate for many years and the parental effects on hatching asynchrony have been largely assumed but not often tested. Some authors suggest that hatching asynchrony depends on the incubation onset and many factors have been shown to influence hatching asynchrony in different species.Our objective was to analyze the exact timing of the onset of incubation and if this affects hatching asynchrony; and,in addition, which other factors (brood patch development, incubation position, adult body condition, intra-clutch eggdimorphism, laying date and year) affect hatching asynchrony in Magellanic penguins Spheniscus magellanicus. We first estimated the eggshell temperature at which embryo development starts, with a non-destructive and novel method. We then recorded individual egg temperatures in 61 nests during incubation, and related them, and other breeding parameters, to hatching asynchrony. We also observed incubation positions in 307 nests. We found a significant positive relationshipbetween hatching asynchrony and the temperature that the first-laid egg experienced during egg laying and between hatchingasynchrony and the initial brood patch area. We also found a negative relationship between hatching asynchrony andthe difference in temperature between second and first-laid eggs within a clutch, measured after the egg-laying period wasfinished. We ruled out position of the eggs during incubation, adult body condition, egg volume, laying date, and studyyear as factors influencing hatching asynchrony. The egg temperature during laying and the difference in temperaturebetween eggs of a clutch are determinants of hatching asynchrony in Magellanic penguins.