Andy Rouse / Great crested grebes (Podiceps cristatus) pair in courtship 'weed dance' in morning light, Wales, UK, February.

Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) courtship weed dance, Cardiff, UK, March.

Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) courtship weed dance, Cardiff, UK, March.

Andy Rouse / Great crested grebe (Podiceps cristatus cristatus) courtship dance at dawn, Cardiff, UK, March.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) pair in 'weed dance' courtship display, The Netherlands, March.

Krijn Trimbos / Great crested grebe (Podiceps cristatus) pair in 'weed dance' courtship display, The Netherlands. March.

David Pattyn / Great crested grebe (Podiceps cristatus) pair performing their 'weed dance' in which they take a vertical position in front of each other and offer plant material to each other. The Netherlands. March...

David Pattyn / Great crested grebe (Podiceps cristatus) pair performing their 'weed dance' during the courting or mating season. The birds offer each other plant material as a present to confirm their bond. The Neth...

David Pattyn / Great crested grebe (Podiceps cristatus) pair performing their 'weed dance' during the courting or mating season. The birds offer each other plant material as a present to confirm their bond. The Neth...

David Pattyn / Great crested grebe (Podiceps cristatus) pair performing their spectacular 'weed dance' during the courting or mating season. The birds offer each other plant material as a present to confirm their bo...

David Pattyn / Great crested grebe (Podiceps cristatus) pair performing their 'weed dance' during the courting or mating season. The birds offer each other plant material as a present to confirm their bond. The Neth...

David Pattyn / Great crested grebe (Podiceps cristatus) adult bird approaching its partner with plant material to perform their 'weed dance'. Mating season. The Netherlands.May 2014