This is a Nazca booby, the second of the three species of booby that I photographed in the Galapagos Islands. Often referred to as a masked booby (although it has recently been classified as a separate species), the Nazca booby is the largest of the three species. They typically lay two eggs, several days apart. If both eggs hatch, the older chick will push the younger chick out of the nest leaving it to die of thirst or cold. The parent will not intervene and the young chick will eventually die. It is believed that this is some sort of insurance policy in case one of the eggs gets destroyed or eaten or never hatches. This mother appeared to have only one egg in her nesting area as she leaned forward to get a better look at my wide angle lens.