Cock of the South... blue bird and rocking horse to occupy plinth

A bronze sculpture of a boy on a rocking horse and a giant bright blue cockerel will take their place on the fourth plinth in Trafalgar Square.

Mayor of London Boris Johnson revealed the winning designs yesterday.

The sculpture, called Powerless Structures, Fig.101, is designed by Scandinavian art duo Elmgreen and Dragset and will be unveiled in 2012. It is intended to question the tradition of large-scale military monuments.

German artist Katharina Fritsch's ultramarine cockerel, designed to symbolise regeneration, awakening and strength, will take its place on the plinth in 2013.

Mr Johnson said: "All of the shortlisted artists show what an extraordinary crucible the fourth plinth is for contemporary art. It continues to spark the imagination and there has been a tremendous response from the public. As we head towards 2012 – a pivotal year for culture as well as sport – these witty and enigmatic creations underline London's position as one of the most exciting cities for art and are sure to keep people talking."

The winners will replace the current work – Yinka Shonibare's large-scale Nelson's Ship in a Bottle.

Other notable artworks which have featured on the empty plinth include Antony Gormley's One & Other, which saw 2,400 people taking the space for an hour to do what they wanted, with some standing naked.

The final selection of the two works from a shortlist of six was made by the members of the Fourth Plinth Commissioning Group including artist Grayson Perry and broadcaster Jon Snow.

The group's chairman Ekow Eshun said: "Elmgreen and Dragset and Katherina Fritsch are distinguished artists with major international reputations.

"Their selection further underlines the importance and reputation of the Fourth Plinth as the most significant public art commission in Britain. Both have created imaginative and arresting artworks."