John Chan / Two male Southern Pacific rattlesnakes (Crotalus oreganus helleri) fighting during mating season. This behaviour is known as a "combat dance", and is used to determine dominance and the right to mate...

Shane Gross / Nurse sharks (Ginglymostoma cirratum) two in a courtship dance at sunrise in a mangrove area near Eleuthera, Bahamas.

David Pattyn / Great crested grebe (Podiceps cristatus) fluffing up its feathers, during courtship dance, whilst its mate dives underwater, The Netherlands. April.

David Pattyn / Black necked grebe (Podiceps nigricollis) pair during courtship performing their courtship dance in the mating season. The Netherlands. April 2014

David Pattyn / Black necked grebe (Podiceps nigricollis) adult bird in breeding plumage approaching its partner in a vertical position during their courtship dance. The Netherlands.April 2014

David Pattyn / Black necked grebe (Podiceps nigricollis) pair swimming away during their courtship dance. The Netherlands.March 2014

David Pattyn / Black necked grebe (Podiceps nigricollis) pair performing their courtship dance in the mating season. The Netherlands.March 2014

David Pattyn / Black necked grebe (Podiceps nigricollis) adult bird spreading its wings and waiting for the submerged partner to appear in front and perform the courtship dance. This is early in the breeding season,...

David Pattyn / Great crested grebe (Podiceps cristatus) performing courtship dance with one emerging from water right in front of the other which has fluffed up its feathers. The Netherlands. April.

David Pattyn / Great crested grebe (Podiceps cristatus) pair wimming very fast next to each other and shaking their heads as a part of their courtship dance. The Netherlands. April.

Steve Gettle / Western Grebe (Aechmophorus occidentalis) pair in courtship dance, North Dakota

Jack Dykinga / Sandhill cranes (Grus canadensis) mating dance at sunset, Bosque del Apache National Wildlife Refuge, New Mexico, USA, December.