A head of a humpback whale and tail of a blue whale are depicted by the six-tonne pieces which are made from willow harvested in Somerset County, England. According to the Avon Wildlife Trust, which manages the site, the area has a whaling history dating back to the 18th Century.

The artwork, named The Bristol Whales, was installed in the city centre last summer to mark Bristol as the first UK city to be named European Green Capital at the start of 2015.

“The River Avon would have been full of the tall-masted ships that made Bristol wealthy, one of which moored at nearby Sea Mills,” said the trust.

“In 1750, Bristol merchants entered the whaling trade, and the ship Adventure brought back two whales, which were rendered to blubber at Sea Mills.

“The venture continued there for almost 50 years.”