The species, which originated in Australia, is common in wildlife parks in the UK, but is rarely sighted in the wild.
However, Sylvia Herbert was able to photograph the creature as it floated on the River Severn in Worcester on Thursday.
The 70-year-old said the area of the river in which she saw the animal is often filled with dozens of water birds, but added she had never spotted a black swan there in three decades living in the city.
“It is quite aggressive - we had actually stopped and I was taking pictures of the cygnets -when we saw this black swan come right up to the side,” she said.
“It doesn’t seem to like the other swans as it keeps chasing them. Black swans are rather striking, they have a different call to the mute swans.
“I’ve lived in the city for more than 30 years but I’ve never seen a black one before. It looks rather beautiful and a rare treat.”
The small number of black swans living wild in the UK are ancestors of birds either released or escaped from captivity.
A study of bird populations in the British Isles in 2012 found there were just 37 confirmed nesting pairs of black swans in the country.
Small populations of the species are known to exist in Marlow, Buckinghamshire, Stockton on Tees and Dawlish in Devon, where the bird has become a symbol of the town.
The last reported sighting of a black swan on the River Severn was in January 2012, when a bird was seen in Upton-upon-Severn.
Join our new commenting forum
Join thought-provoking conversations, follow other Independent readers and see their replies