Masked Booby Chicks
The eggs of the two 4-day old chicks were laid at the same time, but the egg of the fully feathered one hatched 4-5 hours sooner than that of its sibling. This few-hour difference gives that chick an earlier start on the other hatchling by getting fed earlier, and beginning its development sooner. Thus, it is bigger and the stronger of the two, and can grab a larger feeding. The image shows that it has sought to eliminate its sibling competition by pecking out the neck feathers of the weaker, slightly younger sibling. With inadequate food and the denudation reducing its insulation from the sun, it is unlikely the weaker will survive. The parents do nothing to stop the infanticide. [Galapagos Islands].