The brood size of cranes

Abstract

Observations of wild and captive whooping cranes and sandhill cranes, and apparently analogous behaviors in other species with somewhat similar breeding characteristics, suggest that, although the clutch size of both species is normally two eggs, the brood size is usually reduced to one young because of (1) abandonment of the second egg after the first has hatched, or (2) sibling rivalry which results in the death of the weaker chick. This appears to be an innate behavior which is characteristic of several species, and is unrelated to the proximate availability of food.