Blue-footed booby
The blue-footed booby is a specialized fish eater, feeding on small schooling fish such as sardines, anchovies, mackerel, and flying fish. It will also take squid and offal. The blue-footed booby hunts by diving into the ocean after prey, sometimes from a great height, and can also swim underwater in pursuit of its prey. It can hunt singly, in pairs, or in larger flocks. Boobies travel in parties of about 12 to areas of water with large schools of small fish. When the lead bird sees a fish shoal in the water, it will signal to the rest of the group and they will all dive in unison, pointing their bodies down like arrows.
Blue-footed booby
The female blue-footed booby lays two or three eggs. Eggs are laid about four to five days apart. Both male and female take turns incubating the eggs, while the non-sitting bird keeps watch. Since the blue-footed booby does not have a brooding patch, it uses its feet to keep the eggs warm. The incubation period is 41–45 days. Usually, one to two chicks are hatched from the two to three eggs originally laid. The male and female share parental responsibilities. The male will provide food for the young in the first part of their life because of his specialized diving. The female will take over when the demand is higher. Chicks feed off the regurgitated fish in the adult's mouth. If the parent blue-footed booby does not have enough food for all of the chicks, it will only feed the biggest chick, ensuring that at least one will survive.
Like other sexually size-dimorphic birds, female blue-footed boobies usually favor the smaller sex during times of food scarcity. Booby chicks do not show clear differences in size based on sex, but females do grow faster than males, which means they require greater parental investment. Blue-footed boobies display behavior that is described in the Flexible Investment Hypothesis, which states that a female will adjust the allocation of resources to maximize her lifetime reproductive success. This was shown in an experiment in which females had their flight feathers trimmed, so that they had to expend more energy during flights to obtain food for their broods. Female chicks of such mothers were more strongly affected than their brothers, in that they had lower masses and shorter wing lengths.