"Are You My Mommy?"

Macabre Mother's Day sentiments from the natural world:

When Douglas W. Mock of the University of Oklahoma began studying egrets in Texas three decades ago, he knew that the bigger babies in a clutch would peck the smaller ones to death. Still, Dr. Mock was caught off guard by what he saw — or failed to see. He had assumed that the murderous attacks would surely take place while Mom and Dad egret were out fishing.

"I figured that, if the parents were around, they'd try to block these things," he said. "I have three older brothers, and I never would have made it if my parents hadn't interceded."

Instead, Dr. Mock witnessed utter parental indifference. The mother or father would stand by the side of the nest, doing nothing as one chick battered its sibling bloody. "The parent would yawn or groom itself and look completely blasé," said Dr. Mock, author of "More Than Kin and Less Than Kind: The Evolution of Family Conflict." "In the 3,000 attacks that I witnessed, I never saw a parent try to stop one. It's as though they expect it to happen."