Ma. Rodriguezgirones et al., EFFECT OF FOOD-DEPRIVATION ON DOMINANCE STATUS IN BLUE-FOOTED BOOBY (SULA-NEBOUXII) BROODS, Behavioral ecology, 7(1), 1996, pp. 82-88
A pecking hierarchy is normally established in the usual two-chick bro
od of the blue-footed booby (Sula nebouxii). The senior (first-hatched
) chick dominates its smaller sibling and receives a greater share of
parentally provided food. Experimental broods were created by putting
together two unrelated junior chicks of the same age in a vacated fost
er nest. The state of the chicks was manipulated by a period of contro
lled artificial feeding so that each chick underwent a different level
of food deprivation. The resulting dominance relationship depended on
the relative food deprivation level of the chicks: the hungrier chick
normally became dominant. However, the effect of hunger was occasiona
lly overruled by size difference: when the hungrier chick was much sma
ller than its foster sibling, it was unable to gain dominance over its
larger companion. Dominance status is likely to have greater value fo
r the hungrier chick, while the cost of fighting should be lower for t
he larger chick. These results conform to the evolutionarily stable st
rategy predicted for games with asymmetric payoff and differences in r
esource holding power.