A wildlife charity has called for action from the National Grid after five swans were "literally blown apart" after flying into new Hinkley Point C power lines in Somerset.
Pauline Kidner, who is the founder of Secret World Wildlife Rescue, told Sky News that a member of her team went to the scene near Burnham-On-Sea on Monday to find the swans dead on the ground beneath the pylons.
One swan was found still alive and, after assessment by the charity, was later released.
Pictures from the site showed one of the swan's heads had been separated from its body after it struck the power lines.
National Grid has told Sky News it is "investigating as a matter of urgency" and has experts assessing the site.
Ms Kidner said the power lines started to be replaced by National Grid last year - but birds are struggling to see them because "there is nothing on these new ones" to make them stand out.
She said: "We want the National Grid to realise the urgency over this because of the amount of swans in the area. Something needs to be done.
"This is a wetland and it is a good area for swans.
"The power lines started to be replaced last year from Hinkley through to Loxton. Usually, National Grid will put things on the lines so birds can see them, but there is nothing on these new ones.
"When the swans collide with the line, it is an instantaneous death because of the power surge. They were literally blown apart.
"One swan found by the dead bodies was assessed and found to be uninjured. We believe it stayed because its mate was probably one of the dead ones.
"This one was released near a group of young and unpaired swans which winter on the moors.
"Even when this one was being released, three other swans flew over the lines demonstrating this is a flight path, but fortunately avoided them.
"With so many swans already lost through Avian flu, this is an added danger to them. So sad."
Ecological surveys of wintering birds on the Hinkley power line route were previously carried out as part of the environmental assessment for the infrastructure.
A spokesperson for National Grid told Sky News: "The health and safety of wildlife where we work is one of our most important responsibilities.
"We take our environmental responsibilities very seriously and our specialist teams of engineers and ecologists are on site and investigating as a matter of urgency."