The –est Animals

Why crested penguins lay mismatched eggs

Extreme penguin egg favoritism could be quirk of migration

macaroni penguins

MISMATCHED OFFSPRING When macaroni penguins convene at a breeding site (shown), females lay some of the most size-mismatched eggs known among birds.

G. Crossin

By Susan Milius

- More than 2 years ago

In crested penguin families, moms heavily favor offspring No. 2 from the start, and a new analysis proposes why. The six or seven species of crested (Eudyptes) penguins practice the most extreme egg favoritism known among birds, says Glenn Crossin of Dalhousie University in Halifax, Canada.