I found this very interesting article from Scientific American about animal gender behavior:
Bisexual Species: Unorthodox Sex in the Animal Kingdom: Scientific American
Two penguins native to Antarctica met one spring day in 1998 in a tank at the Central Park Zoo in midtown Manhattan. They perched atop stones and took turns diving in and out of the clear water below. They entwined necks, called to each other and mated. They then built a nest together to prepare for an egg. But no egg was forthcoming: Roy and Silo were both male.
My

-girls are all girl...however, my son's Beagle is questionable. Her name is Samantha but, we call her Sammie for short for obvious reasons. She really thinks she's a GUY! My son even dresses her in boy clothes, too! Hmmm...wait a minute, or would that make her a "cross-dresser"...hahaha!!!