Watch video clips from past programmes (7 clips)

Sexual dimorphism

Sexual dimorphism describes animals where there is a physical differences between males and females of the same species (other than in the sex organs). One may be significantly larger than the other, colouration may be different or one might have additional body parts such as antlers, ornate plumage or a mane. In the rarer cases where females are larger or more ornate it is termed reverse sexual dimorphism.

Watch video clips from past programmes (7 clips)

Showing off  

The Life of Birds

Male frigate birds use sight as well as sound to attract a mate.

Role Reverse Birds  

The Life of Birds

Unusual in the bird world, male red phalaropes are duller in colour and care for the young.

Spot the difference  

Autumnwatch

How to tell the difference between a male and female hen harrier.

Fencing whales  

The Living Planet

Male narwhals use their tusk - an overgrown tooth - in courtship.

Flying colours  

Journey of Life

For a male zebra finch, being a pretty boy means you're the fittest mate.

Small, medium or large  

Lost Worlds, Vanished Lives

A huge variety of crest shapes distinguished duck-billed dinosaur species.

Spring plumage  

Bill Oddie Goes Wild

In early spring, ptarmigan begin to change out of their winter white.

Showing off  

The Life of Birds

Male frigate birds use sight as well as sound to attract a mate.

Role Reverse Birds  

The Life of Birds

Unusual in the bird world, male red phalaropes are duller in colour and care for the young.

Spot the difference  

Autumnwatch

How to tell the difference between a male and female hen harrier.

Fencing whales  

The Living Planet

Male narwhals use their tusk - an overgrown tooth - in courtship.

Flying colours  

Journey of Life

For a male zebra finch, being a pretty boy means you're the fittest mate.

Introduction