Intra-clutch factors affecting growth and fledgling success of Magellanic penguin chicks: A crossfos-tering experiment

NAHUEL MARCHISIO; MELINA BARRIONUEVO; ESTEBAN FRERE

Congreso; World Seabird Conference; 2021

Females might adaptively modulate the asymmetries in competiti-ve ability among siblings via egg size dimorphism (ESD) and by differential deposition of resources within a clutch1. Since chicks are fed from the moment they are born, a size hierarchy is genera-ted within the nest by hatching asynchrony (HA) and these asymmetries affects the dynamics among siblings. Evaluate the effect of hatching asynchrony and egg size dimorphism on the growth and survival of Magellanic penguin ?Spheniscus magellanicus? chicks disentangled from pa-rental body condition.ESD gives second chicks a survival advantage, despite hatching asynchrony.Growth of first chicks is only influenced by intrinsic egg factors.Growth of second chicks depends not only on hatching asynchrony and egg size dimorphism, but also on the maternal effect and the father?s body condition.Females in good condition in the pre-laying period could invest more in second eggs than in first eggs, while foster fathers in good condi-tion invest more in rearing of second chicks.